In order to study the ion energy distribution regulation in plasma, the ion energy test principle of grid ion energy analyzer were introduced. The mesh size and the grid spacing of four-grid ion analyzer were respectively simulated by ion optical simulation software Simion7 . 0 . Theoretical analysis results show that when the ion enery is about 800 eV, the mesh size will affect ion energy measurement precision, grid spacing almost do not affect ion energy measurement results. This research results is of important theoretical and practical significance on grid type ion energy testing device design and grid optimization of parameters.