Two kinds of cycloalkoxy silane compounds were synthesized and used as the internal electron donors(IEDs) of supported Ziegler-Natta catalyst for ethylene polymerization to produce polyethylene with broader molecular weight distribution(MWD). The effect of the structure and the amount of these IEDs on the polymerization performance was investigated. The results implied that the molecular weight distribution of the obtained polyethylene could be adjusted by the incorporation of IEDs. SEM result showed that the morphology of catalyst particle was spherical and uniform in size distribution. The titanium content of these catalysts was higher, the active TiCl4 species were easily anchored on the support than that without adding IED, which was determined by ICP. The GPC result confirmed that the polyethylene with broader molecular weight distribution in the range of from 23.4 to 25.6 was obtained using triethoxy-(-cyclopentyloxy)-silane(ED1) and triethoxy-(-cyclohexyloxyl)- silane(ED2) as the internal electron donors. Two kinds of cycloalkoxy silane compounds were synthesized and used as the internal electron donors (IEDs) of supported Ziegler-Natta catalyst for ethylene polymerization to produce polyethylene with broader molecular weight distribution (MWD). The effect of the structure and the amount of these IEDs on the polymerization performance was investigated. The results implied that the molecular weight distribution of the obtained polyethylene could be adjusted by the incorporation of IEDs. SEM result showed that the morphology of catalyst particle was spherical and uniform in size distribution. The GPC result confirmed that the polyethylene with the broader molecular weight distribution in the range from 23.4 to 25.6 was obtained using triethoxy - (- cyclopentyloxy) -silane (ED1) and triethoxy - (- cyclohexyloxyl) -silane (ED2) as th e internal electron donors.