TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The 3C liquid phase selective hydrogenation catalyst is palladium, ruthenium and/or platinum (in weight%) (0.001-1, preferably 0.01-0.15) on a carrier. The carrier is titania, silicon oxide, zinc oxide, tin oxide, molecular sieve, silicon carbide, kaolin and/or cordierte. The catalyst comprises alkali metal, alkaline earth metal, transition metal, rare earth element, arsenic and/or bismuth (0.001-1). The auxiliary active constitute comprises argentine, copper, zinc, gallium, sodium, magnesium, calcium, beryllium, tin, lead, cadmium, strontium, barium, radium, manganese, zirconium, molybdenum and/or germanium (0.001-10), scandium, promethium and/or lanthanum (0.01-15) and arsenic and/or bismuth (0.001-5).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The mixture (c) is cooled without passing through heat exchanger and/or condenser, and directly admitted into gas-liquid separating tank. The un-condensed gas phase material stream (dg) is supplied to fuel gas pipe net or entrances (II-IV) of compressor. The pressure of hydrogenation reactor is adjusted by controlling temperature in inner region of condenser and/or controlling empty flux of the gas phase material stream (dg). The liquid phase material (e1) is mixed with fresh 3C distillate after passing through the heat exchanger, and admitted into selective hydrogenation reactor. The fresh 3C distillate is mixed with material stream (e1) which does not pass through heat exchanger, and admitted into selective hydrogenation reactor. The mixture liquid phase material (e1) and fresh 3C distillate is supplied to propylene rectifying tower for refining. Preferred Material: The fresh 3C distillate (f) is 3C distillate with propylene, propyl, allylene propene and/or allene generated by depropanizer in the generating process of propylene. The content of allylene propane and/or allene in fresh 3C distillation is 0.2-7 mol%. Preferred Conditions: The selective hydrogenation reactor has hydrogen and allylene propane flow rate of 0.6-2, pressure of 1-3.5 MPa, entrance temperature of 5-50 degrees C, and exit temperature of 18-75 degrees C. 3C liquid phase selective hydrogenation reaction catalyst is filled in the reactor to adjust MAPD content in outlet material of the reactor to 0-1000 ppm. The pressure of gas-liquid separation tank is 1-3.5 MPa. The temperature of condenser is 14-70 degrees C. Emptying flux of gas phase flow (dg) is 0-17% of mixed charging rate of 3C distillate and hydrogen (b).