The invention discloses a quadripolymer diesel oil pour point reducer and a preparation method thereof. The method particularly comprises the following steps: (1) weighing a plurality of high alcohols and fumaric acid, and performing esterification reaction to obtain fumaric acid and high alcohols mixed alcohol ester; (2) weighing the fumaric acid and high alcohols mixed alcohol ester, ethylene vinyl acetate, dicyclopentadiene and an initiator, and performing polymerization reaction in a solvent, after the reaction, adding ethanediamine and a catalyst, then continuously reacting, finally performing reduced pressure distillation and alcohol washing on a reaction product to obtain the quadripolymer diesel oil pour point reducer. When the prepared quadripolymer diesel oil pour point reducer is used in No. 0 diesel oil, the pour point reducer can be evenly dispensed in the diesel oil, and the low temperature fluidity of the diesel oil is effectively improved; besides, the preparation method is simple, the raw materials are cheap and easy to get, and when the addition amount is 0.1 percent, the cold filter plugging point of the No. 0 diesel oil can be lowered by 12 to 19 DEG C, and the condensation point can be lowered by 18 to 25 DEG C.