In order to find efficient cold flow improvers for diesel fuels derived from crude oil, copolymers ((RMC)-M-1-MA) were prepared making use of the copolymerization of methacrylate ((RMC)-M-1) of various alkyls with maleic anhydride (MA), and terpolymers ((RMC)-M-1-MA-(RMC)-M-2) were prepared by the reaction of long-chain alkyl methacrylate ((RMC)-M-1), maleic anhydride (MA), and short alkyl methacrylate ((RMC)-M-2). The additives were purified and characterized by IR, H-1-NMR, and GPC. The activities of the synthetic products as the cold flow improvers in two diesel fuels were investigated. The results indicate that: (1) the alkyl chain length of R-1 in R-1 MC-MA copolymers significantly affects the solid point depressing performance. When the long-chain alkyl R-1 is n-C14H29- and the reaction material molar ratio ((RMC)-M-1/MA) is 1:2, the C14MC-2MA possesses the best ASP property; (2) the (C14MC-MA-(RMC)-M-2) terpolymers all demonstrate excellent solid point depression properties when the short-chain alkyl R-2 varies from CH3-to n-C8H17-; (3) however, all of the tested copolymers and terpolymers do not demonstrate necessary cold filter plugging point depression performance. (C) 2004 Elsevier B.V. All rights reserved.