Abstract: The n-alkane content is one of the most important aspects to relate the cryogenic properties of the diesel oil. We can accord to the n-alkane content to design the pour point depressant for diesel oil. On the basis of the mathematical model of the relationship between the n-alkane content and the cryogenic properties of the diesel oil, by selecting the functional group of the diesel oil pour point depressant, the molecule design model of the new-type depressant is obtained. The ratio of different length carbon chains can be calculated by the program developed in our laboratory. According to the designed model, a series of diesel oil pour point depressants with different carbon chains are synthesized. As a result, we can prepared different pour point depressants for different diesel oil. By evaluating the performance of polyacrylate as pour point depressant, the designed model is verified.