The copolymerization of l-octene with styrene catalyzed by rare earth coordination catalysts has been studied for the first time. Some features and kinetic behavior are described. The overall activation energy of the copolymerization was 22.2 KJ/mol and the copolymerization rate could be expressed as R;=K;[Nd] [M];. (=1.68×10;L;/mol;. S, 50℃, [Oct]/[St]=1). The catalytic activity of various rare earth elements in Ln (naph);for the copolymerization was compared and shows the following sequence: Dy, Y, Yb>Ho>Sm, Gd, Nd>Pr>Ce>La>Tm. Both monomers of l-octene and styrene in the copolymerization by Nd (naph);-AlEt;have the tendency of constant proportion copolymerization. The structure of the copolymers was studied by;H-NMR.