Diagonally reinforced coupling beams were proved to have good seismic behaviors by six low frequency cyclic loading experiments with different length to height ratios varying in 1.0, 1.5, 2.0 and 2.5. Based on mechanism analysis of diagonally reinforced coupling beams with the conditions of L/h(length to height ratio)≤1.5 and1.5<L/h≤2.5, a statically indeterminate strut and tie model was proposed to simulate behaviors of diagonally reinforced coupling beams with L/h≤1.5. And 16 formula, such as geometric equation, deformation compatibility equation, physical equation and equilibrium equation were established. Compared with the experiment results, it was found that the model was appropriate for the behavior simulation of diagonally reinforced coupling beams with L/h≤1.5 .