The acceleration and velocity sensors of smart phone are introduced into the experiment ofmeasuring the rotational inertia of a rigid body with three-wire pendulum method.lt makes the periodic processof rigid body oscillation more vivid.Through the “ acceleration-time”and “velocity-timeimages automatically drawn by the mobile phone ,the swing period of the rigid body is obtained , and the rotational inertia of the rigidbody is measured.The results show that the measured data by smart phone sensor are reasonable and therelative error is in the allowable range of experiment. The introduction of smart phone in college physicsexperiment can not only enhance students’cognition of new technology and stimulate students’ desire for newknowledge , but also expand students’ thinking and cultivate students’ spirit of innovation.