Abstract: Lateral pressure test is widely used in the test of geotechnical parameters of soil body. The paper introduced in detail the principles and methods of lateral pressure test, applied them in in-situ test of strongly weathered granite. The experimental results show that the strength parameters of strongly weathered granite are the same as surface cohesive soil. For the rock and soil layer with the same characteristics, the strength index of soil layer is regularly enhancing with depth. Strongly weathered granite in the field has a higher level of resistance capacity to horizontal deformation, but its vertical carrying capacity is lower. Compared with in-situ standard penetration test in some boreholes, results of the two in-situ tests are well correlative.