The optimization of layout of disc cutter is the key to design and stability of cutterhead of composite shield tunneling. A mathematical optimization madel with polar radius and polar angle as design variables and layout principle of disc cutter as constraint is built by analyzing the force on disc cutter. And then the multipurpose functions are optimized by nondominated sorting genetic algorithm calculated by multipurpose Pareto solution, and the optimum scheme is selected. Finally, the optimum scheme is applied to the cutterhead of a composite shield used in a Metro line in Guangzhou. The results show that the radial unbalanced force is reduced by 21.3%; the upsetting moment is reduced by 17.8% and the variance of rock penetration rate is reduced by 15% after adopting the optimized scheme. It is shown that the model and the calculation method are feasible and effective.