A rock triaxial test device and method are provided in embodiments of the invention. The device includes a main frame and a pressure chamber. The main frame is a square frame. The center of the frame is provided with a space for accommodating the pressure chamber. The pressure chamber includes a cylinder and a pedestal. The cylinder and the pedestal are detachably fixed through a split type clamp to form a sealed inner cavity. An upper pressing head and a lower pressing head are disposed in the cylinder, and are opposite to apply axial pressure on a test piece. The pedestal is provided with a confining pressure inlet outlet to apply radial pressure on the test piece. An axial extensometer and a radial extensometer are disposed in the cylinder. The top of the cylinder is provided with a vent port. The lower pressing head is provided with a gas inlet. The device also comprises a pressure chamber confining pressure servo loading mechanism for providing the pressure chamber powder required for testing.