The invention discloses a maintenance system of locomotive brake control software. Distributed network function modules are used as multiple nodes of a CAN bus, after the parallel connection of the distributed network function modules through the CAN bus, a unified electrical connection interface is employed to connect a maintenance terminal, and the distributed network function modules have unique ID data. The maintenance terminal connects a CAN network to a control terminal and is used for carrying out format conversion and transceiving on control terminal network and CAN network data. The control terminal is connected to the maintenance terminal and is used for receiving the ID data of a node to be maintained inputted by a user, and selects a corresponding node execution program from the distributed network function modules to perform the operation of program downloading or data monitoring. It can be seen that the intelligent maintenance of multi node control units can be realized, the operation steps are simplified, the maintenance difficulty is reduced, the maintenance efficiency is improved, and the intelligent level of software maintenance is improved. In addition, the invention provides a data processing method of the maintenance system of the locomotive brake control software.