TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The film pre-formation process comprises: (i) adding the clean surface water to a biochemical reaction basin and aerating for the half of the day; (ii) adding the bacilli which is 0.1 mass% of clean water in the biochemical reaction basin to the biochemical reaction basin; adding glucose to the biochemical reaction basin and controlling the chemical oxygen demand (COD) of the water body inside the biochemical reaction basin to 800 plus minus 20 mg/L; at the same time, adding rapeseed cakes, wheat bran, inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin respectively; according to 100 mg, 10 mg, 2000 mg and 5000 mg per liter of clean water in the biochemical reaction basin; (iii) aerating the biochemical reaction basin to keep the dissolved oxygen concentration in the clean water of the biochemical reaction basin to 1-3 mg/L; and (iv) subjecting the biochemical reaction basin to sealed aeration for 2 days and operating for 3 cycles each of which contains 24 hours, where each cycle is performed via settling for 2 hours and changing supernatant accounting for 0.25 of the volume flow rate of clean surface water; adding the glucose to the biochemical reaction basin to control the COD of the water body in the biochemical reaction basin to 800 plus minus 20 mg/L; adding inorganic phosphate and inorganic ammonium salt into the biochemical reaction basin to control the ratio between carbon (C), nitrogen (N) and phosphorus (P) to 100:5:1; and aerating the biochemical reaction basin to keep the dissolved oxygen concentration in the clean water of the biochemical reaction basin to 1-3 mg/L. The process of forming film of oily sewage and starting comprises (1) stopping the aeration everyday and statically settling for 2 hours; replacing the supernatant of a 0.33-volume flow rate by oily sewage with the oil content less than or equal to 20 mg/L and the sulfide content of less than or equal to 10 mg/L and adding glucose, inorganic phosphate and inorganic ammonium salt to control the COD and the ratio between C, N and P of sewage in the biochemical reaction basin to 500 plus minus 20 mg/L and 100:5:1 respectively; 50 mg/L of bacilli of the film pre-formation process is added; aerating the biochemical reaction basin everyday to keep the dissolved oxygen concentration in the sewage of the biochemical reaction basin to 1-3 mg/L; (2) on the ninth day, continuously feeding oil field oily sewage with the oil content of less than or equal to 20 mg/L and the sulfide content of less than or equal to 20 mg/L to the biochemical reaction basin at the intake velocity of 10% of that of biological-treatment oily sewage and adding inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin to control the ratio between C, N and P to 100:5:1 and make the dissolved oxygen concentration in the sewage of the biochemical reaction basin of greater than or equal to 4 mg/L; (3) on the tenth day, continuously feeding oil field oily sewage with the oil content of less than or equal to 20 mg/L and the sulfide content of less than or equal to 20 mg/L to the biochemical reaction basin at the intake velocity of 20% of that of biological-treatment oily sewage and adding inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin to control the ratio between C, N and P to 100:5:1 and make the dissolved oxygen concentration in the sewage of the biochemical reaction basin at greater than or equal to 4 mg/L; (4) on the eleventh day, continuously feeding oil field oily sewage with the oil content of less than or equal to 20 mg/L and the sulfide content of less than or equal to 20 mg/L to the biochemical reaction basin at the intake velocity of 30% of that of biological-treatment oily sewage and adding inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin to control the ratio between C, N and P to 100:5:1 and make the dissolved oxygen concentration in the sewage of the biochemical reaction basin at greater than or equal to 4 mg/L; (5) on the twelfth day, continuously feeding oil field oily sewage with the oil content of less than or equal to 30 mg/L and the sulfide content of less than or equal to 30 mg/L to the biochemical reaction basin at the intake velocity of 45% of that of biological-treatment oily sewage and adding inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin to control the ratio among C, N and P to be 100:5:1 and make the dissolved oxygen concentration in the sewage of the biochemical reaction basin at greater than or equal to 4 mg/L; (6) on the thirteenth day, continuously feeding oil field oily sewage with the oil content of less than or equal to 30 mg/L and the sulfide content of less than or equal to 40 mg/L to the biochemical reaction basin at the intake velocity of 60% of that of biological-treatment oily sewage and adding inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin to control the ratio between C, N and P to 100:5:1 and make the dissolved oxygen concentration in the sewage of the biochemical reaction basin at greater than or equal to 4 mg/L; (7) on the fourteenth day, continuously feeding oil field oily sewage with the oil content of less than or equal to 40 mg/L and the sulfide content of less than or equal to 50 mg/L to the biochemical reaction basin at the intake velocity of 80% of that of biological-treatment oily sewage and adding inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin to control the ratio between C, N and P to 100:5:1 and make the dissolved oxygen concentration in the sewage of the biochemical reaction basin at greater than or equal to 4 mg/L; and (8) from the fifteenth day, continuously feeding oil field oily sewage with the oil content of less than or equal to 50 mg/L and the sulfide content of less than or equal to 50 mg/L to the biochemical reaction basin at the intake velocity of 100% of that of biological-treatment oily sewage and adding inorganic phosphate and inorganic ammonium salt to the biochemical reaction basin every day to control the ratio between C, N and P to 100:5:1 and make the dissolved oxygen concentration in the sewage of the biochemical reaction basin at greater than or equal to 4 mg/L. Preferred Component: The inorganic phosphate is sodium phosphate, potassium dihydrogen phosphate or diammonium phosphate. The inorganic ammonium salt is ammonium chloride, urea or diammonium phosphate.