The invention discloses a rock-soil pressure shear rheological testing machine and a testing method, the testing machine comprises a mainframe, a vertical loading system and a horizontal loading system are provided on the mainframe, and a servo oil pressure system controlled by a computer provides oil pressure to the vertical loading system and the horizontal loading system. According to the invention, a shearing apparatus, the horizontal loading system, a servo hydraulic system and an electric control system are added for realizing automation, control and accuracy of the tests. An original waste and old press mainframe and a vertical oil cylinder are used by the testing machine, thereby about 50% of cost can be saved, the testing machine aims at test materials such as rock, rock mass and soil/stone compound body, and can perform with the following tests: a compression test, a shearing test, a residual strength shearing test, a compression rheological and shearing rheological test.