Direct shear apparatus for testing shear strength can used to test shear strength of rock interfaces and joints and get stable mechanical shear strength parameters. An improved testing principle was introduced based on the existing defects of direct shear apparatus. Then, measurement and control system of the direct shear apparatus was developed. Quasistatic and dynamic compressive testing under heavy and low load were done, and the reliability and accuracy met the test requirements. The direct shear apparatus support to research shear strength.