TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Preparation of (I) comprises (a) raising the temperature of the molecular sieve material from room temperature to 330-370 degrees C at a rate of 1 degrees C/minute for 1-2 hours, and continuously raising the temperature to 550-600 degrees C at a rate of 1 degrees C/minute for 8-12 hours, (b) dissolving soluble cobalt salt and soluble chromium salt with needed amount in de-ionized water for preparing a solution (1-2 mole/l) which is a precursor solution for preparing a catalyst, (c) soaking the molecular sieve obtained in step (a) into the precursor solution containing active ingredient, where the weight ratio of the molecular sieve to the solution is 1:10-1:2000, mechanically stirring or magnetically stirring the mixture for 1-4 hours with an ultrasonic-assistant oscillation manner, and treating the mixed solution for 1-10 hours to obtain a mixture solution, (d) uniformly stirring the mixture solution, heating the solution at 60-80 degrees C for 1-12 hours and then drying at 100-120 degrees C for 4-24 hours, and (e) roasting the product obtained in step (d) at a temperature of 500-700 degrees C for 2-6 hours to obtain a catalyst product. Preferred Method: In the method, the mechanically stirring speed or the magnetic stirring speed is carried out at a speed of 200-600 revolutions per minutes (rpm). Preferred Components: The loading capacity of the cobalt and the chromium on the molecular sieve is 1%, preferably 20%. The mole ratio of cobalt/chromium is 1, preferably 1:2%. The soluble cobalt salt is cobalt nitrate, cobalt acetate or cobalt chloride. The soluble chromium salt is chromium nitrate, chromium acetate or chromium chloride. The volume concentration ratio of oxygen/methane in the reaction gas is 5-100. The appropriate space velocity of the oxygen/methane is 5000-100000/hour. The reaction pressure of the oxygen/methane is normal pressure. The appropriate operation temperature of the oxygen/methane is 250-600 degrees C.