TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation: The preparation method of the metal carbide catalyst of CO hydrogenation synthesis reaction comprises (1) taking the mixture of VIA acid ammonium salt to transition metal compound or rare earth metal compound with a mole ratio of transition metal or rare earth metal to VIA metal of 0.1-1.0:1, calcining the mixture at 400-600 degrees C for 2-4 hours to obtain precursor of VIA metal oxide or precursor of composite oxide of VIA metal with transition metal or rare earth metal; (2) grinding oxide precursor into powder less than 0.3 mm and putting it into quartz reactor; (3) mixing hydrocarbon with less than 4 carbons, CO, or carbon dioxide (CO2) with hydrogen gas according to volume ratio of 1:3-9 to compound carbonized medium, filling the oxide precursor and carbonized medium into reactor with speed of 1.0 g:(10-100) ml/minute, heating up to 400 degrees C from door temperature with a rising speed of 5-20 degrees C/minute, keeping the constant temperature in carbonization final temperature for 2-5 hours, cooling in inert atmosphere quickly to obtain the material; (4) deactivating the material in deactivating gas with oxygen volume concentration of 0.5-2% for 2-9 hours to obtain VIA carbide or double-metal carbide catalyst; (5) soaking the alkali metal or alkali-earth metal with equivalent volume or mixing the alkali metal or alkali-earth metal with VIA carbide or double-metal carbide catalyst according to the mole ratio of 0.04-0.8:1, calcining the mixture at 400-600 degrees c for 2-5 hours, and cooling it in inert atmosphere with oxygen volume concentration of 0.5-2% for 2-9 hours to obtain alkali metal or alkali-earth metal modified catalyst. Preferred Components: The VIA acid ammonium salt is ammonium molybdate, ammonium tungstate, or ammonium chromate. The transition metal compound is V IIB or VIII metal compound. The V IIB transition metal compound is nitrite or acetate of manganese or technetium, the VIII transition metal compound is nitrite or acetate of iron, cobalt or nickel. The rare-earth metal compound is nitrite of lanthanum or cerium. The inert atmosphere is nitrogen gas, argon gas, and/or helium gas. The deactivating atmosphere is air or oxygen and nitrogen, argon gas or helium gas and their mixture. The alkali metal compound is carbonate, hydroxide, or organic alkali metal salt of lithium, sodium, potassium, and cesium. The alkali-earth metal compound is carbonate, hydroxide or organic alkali metal salt of magnesium and calcium. Preferred Conditions: The use condition of the catalyst comprises reaction temperature, pressure, airspeed, and molecular hydrogen (H2)/CO ratio of 260-360 degrees C, 1.0-10.0 MPa, 1000-8000 per hour, and 0.8-1.8, respectively.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The hydrocarbon with less than 4 carbons is methane, ethane, propane, butane, ethane, propylene, and/or butylenes.