Ethylene polymerization catalyzed by Ni and Pd catalysts is an area of great interest both in academic research and for industrial production. The structures of Ni and Pd catalysts can dramatically influence polymerization performance. In this review, the influence of newly reported Ni and Pd catalysts on ethylene polymerization, from ligand effects to metal-metal co-operativity, as well as the polymerization conditions, are discussed to provide fresh guidelines for rational design of highperformances catalysts, highly efficient study of polymerization mechanisms, and successful synthesis of PE variants with unique microstructures and properties.