The research was carried out on the parameter optimization of milling titanium alloy in this paper. The cutting models including cutting force, tool life and machined surface roughness are obtained by orthogonal array experiments. The maximum metal removal rate, MRR is selected as objective function. The constraints related to machine tool, workpiece, cutting tool and other machining situations are presented in details. Genetic algorithm is used to search for the optimum milling parameters for the maximum metal removal rate of titanium alloy. The optimization results show the optimization system can improve the productivity of milling Ti6Al4V obviously.