2,2-Dinitropropyl acrylate - styrene (DNPA-St) copolymer was synthesized by free radical polymerization in ethyl acetate by using azobisiosbutyronitrile as initiator. The structure and properties of DNPA-St copolymer were also characterized by FTIR,¹H NMR and DSC measurements. The behavior of the copolymerization between 2,2-dinitropropyl acrylate (DNPA) and styrene (St) was studied,the composition of the copolymer was determined using infrared spectrum method, and the reactivity ratios of DNPA and St were measured. Results show that the reactivity ratios of DNPA and St was obtained by using the Fineman-Ross method,r_DNPA=0.911 and r_St=0.038,respectively. The polymerization of DNPA with St is a non-ideal copolymerization,and the products are random copolymers. The glass transition temperature and thermal decomposition temperature of the DNPA-St copolymer is 63.3 ℃ and 251.4 ℃. It is compatible with RDX and HMX,and thermal stability.