The invention discloses a terpolymer composite petroleum pour point depressant and a method for preparing the same, wherein the pour point depressant is formed by the random copolymerization of maleic anhydride monomer, 2-methacrylate and carboxylic acid ethylene ester, and the weight average molecular weight is between 10, 000 and 90, 000g/mol. The invention also discloses a terpolymer composite petroleum pour point depressant composite which consists of the following components in weight percentage: 55 t0 92 percent of the terpolymer composite petroleum pour point depressant and 8 to 45 percent of surfactant. The pour point depressant and the pour point depressant composite have the advantages of obviously improving the low-temperature rheological property of crude oil, improving the quality and efficiency of operations such as crude oil exploitation, collection-transfer, storage and the like, widening the cutting width of fraction during the crude oil refining and lowering the energy consumption of pipe transportation.