Spherical MgCl2 supported metallocene catalyst was prepared by supporting MAO on carrier which was prepared from MgCl2·nEtOH．Ethylene polymerization was carried out by addition of MAO／MgCl2

different metallocenes and alkylaluminum

in the absence of soluble MAO．It shows high activity for ethylene polymerization at lower Al／Zr(Al/Zr=45)．The effect of concentration of Al(i-Bu)3 on polymerization activities and activation of Et(Iad)2ZrCl2 were studied．Kinetic behavior of ethylene polymerization on spherical Mgcl2 supported metallocene catalyst was investigated

which indicated the polymers obtained by reaction could affect the diffusion of ethylene in hexane under the experiment condidtion．Different aluminium alkyls have great impact on the whole polymerization behavior

and the relative reactivity decreases in the following order：Al(i-Bu)3＞AlEt3＞AlMe3＞AlEt2Cl

in which Al(i-Bu)3 shows the highest catalytic activity (5.78×107 g PE/mol-Zr·h)．