The foundation soil of port is mostly unsaturated soil. The strength characteristics of soil under different matrix suction are different and difficult to predict accurately. Taking unsaturated silty clay of a port foundation project in Fujian Province as the research object，we carry out soil-water characteristic curve test，saturated and unsaturated triaxial compression test. According to the near linear characteristics of section AB in the soil-water characteristic curve，we assume that the volume water content is linearly related to the matrix suction pair value，take the data of points A and B as the known conditions，and establish the relationship between matrix suction logarithm and relative saturation Se. Based on the Vanapalli strength prediction model，we construct a new unsaturated soil strength prediction model，give the parameter solution method，and predict the strengths of three kinds of unsaturated soils by the new prediction model based on the test data of unsaturated organic matter silt and expansive soil in relevant literature，which is compared with the traditional prediction method. The results show that the strength identification effect of the new prediction model is good，and it is feasible and applicable to the strength prediction of unsaturated silty clay，organic clay and expansive soil.