The two-step phase-shifting method is an important method to balance high speed and high precision in fringe projection profilometry. However, the current solution algorithm has low accuracy or high algorithm complexity. This paper presents a two-step phase-shifting solution method based on variable grouping optimization. In this method, the original iterative variables are divided into linear group variables and nonlinear group variables. For the determined nonlinear group variables, the explicit optimal solution of linear group variables can be obtained by the least square method. By optimizing the parameters of the nonlinear group, the global optimal solution is obtained. The method in this paper is verified by the numerical simulation and experiment. The results show that the method in this paper effectively reduces the possibility of falling into the local optimum of the phase value obtained by the multivariate nonlinear optimization and reduces the complexity of the algorithm.