Non-contact coaxiality measuring method is proposed. The surface concentricity of hollow cylinder is measured by using two-dimensional laser displacement sensor. Requirements are put forward for the speed of the turntable mounted to the object based on the sensor sampling rate. According to the diameter of the inner cylindrical surface,the method and design skills to select a two-dimensional laser displacement sensor are given. The factors affecting the measurement accuracy are analyzed in detail. Experiment results show that the measuring device is easy to implement and has high accuracy.