Straw has relatively high tensile strength, as a kind of aggregate, combined with cement, gypsum and other bonding materials, which can improve the strength of the benchmark materials and control the initiation and propagation of microcracks. The physical and mechanical properties of straw-mortar composite materials are determined by the property of straw itself, the bonding capacity of matrix materials, the environment and other factors. In this study, three-factor and three-level regression analysis experiment was carried out by using Design-Expert software to obtain the optimal physical and mechanical properties and mix ratio of rice straw-mortar composite materials. The highest compressive strength, dry density and the lowest water absorption rate of rice straw-mortar composite materials were 3.06 MPa, 1.340 g·cm-3 and 20.8%, respectively, and the corresponding gypsum content, straw length, and straw content were 15%, 20 mm, and 15%, respectively. After 15 times freeze-thaw (F-T) between − 20 ℃ and 20 ℃, the strength loss rate, mass loss rate and water absorption rate of rice straw-mortar composites produced in different conditions varied from 32.2–47.3%, from 2.1–4.5%, and from 22.6–42.2%, respectively. The above experimental results indicated that the rice straw-mortar composite materials could meet the actual using demand of self-bearing wall whether to experience F-T, which laid a certain foundation for the popularization and application of rice straw-mortar composite materials in non-bearing wall.