Abstract: In order to reduce the effect of dry cracking on the protective effect of rice straw in ecological protection of granite residual soil slope, the effect of rice straw reinforcement rate on soil cracking behavior and the interaction between rice straw and soil are examined by the cracking test of reinforced soil under the simulated temperature and simulated sunshine conditions. The results show that the samples with the straw reinforcement rates of 0.3%, 0.4% and 0.5% at room temperature do not crack at room temperature. According to the width of the crack growth rate, the cracking process of reinforced soil samples under simulated sunshine conditions can be divided into 4 stages: slow development Ⅰ, rapid development Ⅱ, slow development Ⅲ and stable development Ⅳ. Rice straw reinforced has a moisturizing effect on the samples. But too much blending ratio will lead to the gap in soil to increase, which provides a convenient channel for water to escape into the atmosphere. In this paper, the limit reinforcement ratio of the rice straw reinforced soil cracking should be 0.3% ~ 0.4%, and the results provide reference for the protection of the ecological design of rice straw reinforced soil.