Abstract: According to the experimental data of frame grids and composite walls, the paper analyzes the mechanical characteristics of the ecological filled blocks and frame grids. The twin shear unified strength theory is adopted, in which the influence of intermediate principal stress 2 is considered and it is applied to various materials of different performance in tension and compression under complex stress state. Based on the unified strength theory, the width expression of equivalent oblique compression strut is deduced, and the calculated values and experimental values are compared. The results show that the width expression works for ecological composite wall filled with different ecological materials, and the numerical results agree well with experimental ones. In addition, this model is capable of analyzing the dynamic characteristics of composite walls.