The new type heterogeneous combined catalyst system TiCl4-(α-diimine)nickel(Ⅱ)complexes/MgC12-SiO2/A1R3 was prepared. Ethylene and 1-butene were copolymerized with thecatalysts in slurry phase. It was found that with combined catalyst, the copolymers with lowerdensity and higher branched degree were obtained. 13CNMR results showed that in the obtainedcopolymers existed not only ethyl but also some other kinds of branches due to the fact thatethylene exhibits the behavior of oligomerization and copolymerizafion in-situ with combinedcatalysts.