The invention provides a train speed automatic control method based on PID and a filtering algorithm. The method includes the steps of obtaining the current running target speed and actual speed of atrain, calculating speed tracking errors, calculating error deviation and updating the state amount of an error deviation differential filter, calculating a PID control amount and updating the state amount of a PID controller in the integral process, adjusting the PID control amount, modifying the adjusted PID control amount, updating the modified PID control amount, converting the updated PID control amount into corresponding control force and modifying the control force, and outputting the modified control force to the train. In combination with the advantages of the filtering algorithm anda PID control algorithm, deviation modification is conducted on the speed tracking errors, the speed tracking errors in the train driving process are reduced, the train is more precisely controlled, it is ensured that the train can more smoothly and stably run, and the sitting comfort degree is improved.