The sensitivity analysis of soil moisture to soil texture (sand and clay) was studied by using the common land model and meteorological forcing data from January 1, 2008 to September 31, 2009 at the Arou Observation Station in Heihe river basin. The SCEUA algorithm was utilized to optimize the soil texture and soil hydraulic parameters separately and the impact of the result of soil moisture with different strategies was analyzed. The result shows that surface moisture is quite sensitive to soil texture, the sensitivity coefficients are larger than 0.45, and the sand percentage is more significant to the soil moisture; SCE-UA algorithm is used to optimize the soil texture or soil hydraulic parameters which can effectively improve the accuracy of soil moisture simulation. However, optimizing soil hydraulic parameters will likely lead to the apperance of the phenomenon of equifinality for different parameters, while optimizingsoil texture can constrain the range of soil hydraulic parameters and make them more reasonable.