Abstract: The heterotypic space grid structure (HSGS) is featured with complex mechanical behavior, a variable structural shape and a strong correlation relationship among structural parameters. HSGS's optimization has always been a challenging subject. By studying geometrical characteristics and mechanical behavior of HSGS, a multilevel optimization method was proposed to minimize the HSGS weight. In the first stage, the strength and stability of HSGS members were optimized in the local constraint. In the second stage, the overall stiffness and stability of HSGS were optimized in the overall constraint. The computational optimization method for HSGS was realized by combining the discrete variable optimization design theory with the relative difference quotient algorithm. The multilevel optimization method of HSGS was programmed by using the ANSYS parameterized language. The validity of the optimization method and program were testified by comparing the results of a real engineering case from the multilevel optimization method with the results of the MST software.