A kind of crosslinking copolymer as solid–solid phase change material (PCM) is synthesized by copolymerization. The scope of PCM applications is often severely limited by their heat stablility and phase transition state. The solid–solid phase change materials we obtained retain basic state during phase change transitions. The crosslinking polymer is heat stable under 300° and the latent heat of crystalline and latent heat of melting is on the average of 120 J/g and 140J/g, respectively. The property of thermal stability and heat storaged is related to crosslinking density of the gel. The property of thermal stability and high latent heat may expand the scope of PCMs applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39755.