Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel catalystsystems based on Cu (Cu(CH_3COO)_2/ligand/acid) were firstly reported for the copolymerization of ethylene with carbonmonoxide, in which the ligand was a bidentate phosphorus chelating ligand. The experimental results showed that this kindof Cu catalyst system exhibited high activity. When DPPP (1, 3-bis(diphenylphosphine)propane) and CH_3COOH were usedas ligand and acid, the corresponding catalyst system had the best activity of 108.1 g copolymer/(gCu·h). The novel Cu catalyst system had the advantages of high stability and low cost. Copolymerization of ethylene with carbon monoxide was pertormed with Cu catalyst systems. Novel campaignsystems based on Cu (Cu (CH_3COO) _2 / ligand / acid) were reported for the copolymerization of ethylene with carbonmonoxide, in which the ligand was a bidentate phosphorus chelating ligand When DPPP (1,3-bis (diphenylphosphine) propane) and CH_3COOH were used as ligand and acid, the corresponding catalyst system had the best activity of 108.1 g copolymer / ( gCu · h). The novel Cu catalyst system had the advantages of high stability and low cost.