A distributed model-free adaptive PID(MFAPID) control scheme with traction/braking force constraints and rear-end protection is proposed for a class of multi-train systems. Firstly, the dynamic linearization method is used to transform the train dynamics model into an equivalent dynamic linearization data model. Secondly, by introducing saturation function and collision avoidance feedback mechanism, a distributed MFAPID control algorithm with traction/braking force constraint and rear-end protection function is designed by using I/O data, and the convergence of the algorithm is proved by compression mapping method. Finally, the effectiveness and stability of MFAPID control algorithm are verified by numerical simulation and comparison experiments.