A method and system for monitoring a rail vehicle are provided. The method includes: a local device acquires current operating data and historical operating data of a rail vehicle from a controller of the rail vehicle, herein the local device, which is connected with the controller, is a portable testing device; the local device obtains fault information according to the current operating data and the historical operating data, herein the fault information includes at least one of a fault code and a fault description; the local device obtains a maintenance plan corresponding to the fault information, herein the maintenance plan is obtained through a remote device or a server side; and the local device maintains the rail vehicle according to the maintenance plan. The disclosure solves a technical problem in the traditional art that a troubleshooting process of a rail vehicle is difficult, and when the rail vehicle has a fault, the fault cannot be solved timely.