The measurement of gravitational acceleration by a single pendulum is a basic content in the physicsexperiment of the university ,and it is also a conventional method to measure the aeceleration of gravity , in the experiment ,three measurement tools are usually used to measure the period,such as a smart phone ,a multi-funetion timer and 'Tracker software."'he experimental results show that the accuracy of the three measurementtools is in descending order: 'Tracker software , multi-funetion timer, and smart phone. In the experiment , thesingle pendulum period is often affected by the movement of the conic pendulum and produces errors ,and the analysis of Tracker software shows that the movement of the single pendulum will lead to the small gravitation alacceleration of the measured gravity.