Tandem catalytic systems, consisting of ethylene bis(indenyl) zirconium dichloride with two different cocatalysts, alkylaluminum(diethylaluminium chloride or trialkylaluminum) and methylaluminoxane, were employed in preparing branched polyethylene from ethylene as sole monomer. The catalytic system rac-Et(Ind)2Zr Cl2/Al Et2Cl/MAO exhibited high incorporation(29.0/1000C). The oligomerization and copolymerization reaction conditions in the tandem catalytic system, as well as the different cocatalysts, have effects on the catalytic activity and the properties of the obtained polymer, such as melting temperature, crystallinity, molecular weight and molecular weight distribution. Moreover, the oligomerization reaction condition is the main factor in altering the properties and structures of polyethylene. Tandem catalytic systems consisting of ethylene bis (indenyl) zirconium dichloride with two different cocatalysts, alkylaluminum (diethylaluminium chloride or trialkylaluminum) and methylaluminoxane, were employed in preparing branched polyethylene from ethylene as sole monomer. The catalytic system rac- Et (Ind) 2Zr Cl2 / Al Et2Cl / MAO exhibited high incorporation (29.0 / 1000C). The oligomerization and copolymerization reaction conditions in the tandem catalytic system, as well as the different cocatalysts, have effects on the catalytic activity and the properties of the obtained polymer, such as melting temperature, crystallinity, molecular weight and molecular weight distribution. Moreover, the oligomerization reaction condition is the main factor in altering the properties and structures of polyethylene.