A kind of novel bridged nonmetallocene catalysts was synthesized by the treatment of NN-imidazole and NN-phenylimidazole with n-BuLi, and MCl4 (M = Ti, Zr) in THF. Those catalysts were performed for ethylene polymerization after activated by methylaluminoxane (MAO). The effects of polymerization temperature, Al/M ratio, pressure of monomer, and concentration of catalysts on ethylene polymerization behaviors were investigated in detail. Those results revealed that the catalyst system was favorable for ethylene polymerization with high catalytic activity. The polymer was characterized by C-13 NMR, WAXD, GPC, and DSC. The result confirmed that the obtained polyethylene featured broad molecular weight distribution around 20, linear structure, and relative low melting temperature. (c) 2007 Wiley Periodicals, Inc.