The invention discloses an environment-friendly high-performance quickly de-molding polyurethane reaction injection molding compound and a preparation method of a self-catalyzed chain extender thereof. The compound is prepared from two components. The component A is prepared from 1 to 10 percent of self-catalyzed chain extender and 0.01 to 2 percent of composite catalyst, wherein the self-catalyzed chain extender is the matter with the following structure shown in the description, in the formula, x is equal to 2 to 5, R is CyH2y+1, and y is equal to 0 to 2; and the composite catalyst is prepared from 10 parts of bismuth isooctanoate, 1 to 2 parts of potassium isooctanoate, 15 parts of bicyclic amidine compound and 10 parts of glycerol. The component B is prepared from 60 to 95 percent of MDI (diphenylmethane diisocyanate), 5 to 40 percent of modifier and 23 to 28 percent of NCO (isocyanate), wherein the modifier is prepared from at least one dihydric alcohol and at least one triatomic alcohol. The preparation method of the self-catalyzed chain extender comprises the following steps of heating piperazine to 65+/-5 DEG C, at a temperature constant state, slowly dropping one of ethylene oxide, propylene epoxide or epoxybutane into a reaction vessel according to molar ratio, after dropping is finished, increasing the temperature to 80 to 85 DEG C to react for 4 hours, cooling, and discharging materials. The compound is low in odor, low in VOC (volatile organic compounds), good in weather resistance and short in de-molding time.