The invention discloses a train velocity curve tracking control method and system based on event triggering PID control and belongs to the field of city rail train operation control technologies. Themethod comprises the steps that a single-particle motion simulation model with basic resistance being zero when a train is started is established; the actual motion state of the train is collected, and a motion state difference is acquired according to an expected motion state at a corresponding sampling time point in the single-particle motion simulation model; whether the motion state differencemeets a control update triggering condition or not is judged; and if yes, whether control state update is triggered or not is judged according to an absolute value of the motion state difference andthe change rate of the motion state difference. Through the control method and system, the number of times of calculation and burden on a controller are lowered, the fault rate is lowered, and prolonging of the service life of hardware is benefited; and it is guaranteed that the minimum interval between two update moments of a train-mounted control system has a lower bound, and the ZENO phenomenoncannot occur.