Abstract：After the excavation of the Three Gorges Project(TGP) shiplock slope，a larger tension stress area is seen because of unloading and stress redistribution，where the rockmass is shown on a tension-shear stress state. The laboratory rock tension-shear tests are carried out to study the strength criterion of the tension stress area. However，the in-situ rockmass test to analyze the criterion is seldom seen. Based on the in-situ tension-shear test with the size of 50 cm×50 cm in the TGP shiplock slope rockmass，the test results show that the tension-shear strength of rockmass is reduced continually as the tension stress increases；and the relationship between and has a obvious curve characteristic. The achieved conclusion of tension-shear strength criterion can be drawn that the rockmass tension-shear strength criterion should adopt the second-degree parabola model best；and the next preferable choice of criterion is hyperbola model. However，the beeline model applied to the tests will cause a considerably larger discrepancy. Consequently，when carrying on the deformation stability analysis to side slope，the strength criterion of beeline model to analyze the rockmass of tension-shear stress area should be avoided；and the beeline model relationship，which is obtained from the laboratory press-shear test of rock，can not be used to determinate the tension stress zone.
