Abstract: In order to solve the problems that the mechanical properties of uniform lattice structure cannot be fully achieved under different boundary conditions, as well as the difficulty of modeling the graded lattice structure, a parametric design and optimization method of graded lattice structures is proposed. Firstly, the model of lattice structures is represented by STL format, and the relationship between design parameters and relative density of lattice structures is developed to realize the parametric design of graded lattice structures; Then, the relationship between relative density and equivalent mechanical properties of lattice structures is obtained using the homogenization method; Finally, the density optimization model of graded lattice structure with the minimum compliance of structure under boundary conditions and relative density constraints is established and solved. The experimental results of a three-point bending beam model show that the bending stiffness of the optimized model is increased by 147.2% and the maximum load-bearing capacity is increased by 82.31%, which verifies that the proposed method is feasible and effective.