Abstract: Some small section steel soil-cement walls are applied to foundation pit support in stance. But there isn’t acquainted with the wall’s action mechanism. Through the bending experiments on small H-Steel soil-cement model beam, basedon the similarity theory, the combined action mechanism of section steel and soil-cement in the model beam is set forth in this paper. The experiments showed that the soil-cement made great contributions to the rigidity of compound beam and also showed that both section steel’s and soil-cement’s contri butions to the rigidity changed before or after the soil-cement cracking. Therefore, the con cept is given of soil cement and section steel relativity rigidity contribution coefficient, the ri gidity formula of compound beam and the acquisition value of the rigidity Contribution coeffi cient. The frictional resistance is obtained between the clay (or sand) soil-cement and the section steel. This frictional resistance is a direct proportion to the soil cement strength. The different compound form of double section steel ends has a little influence onthe soil cement rigidity contribution coefficient and the cracking uhimate deflections. The cracking ultimate deflections of the compound beam are also obtained, h concludes that the double section steel hinged girder is more applicative in the practice under the analysis of combined action mechanism.