A detachable vehicle-mounted storage box for electric power spare parts is a rectangular box body which is defined by a front side wall, a rear side wall, a left side wall, a right side wall and a bottom plate. The rear side wall of the box body is fixed on a longitudinal side wall on the left side of an engineering van carriage through bolts. The detachable vehicle-mounted storage box for the electric power spare parts has the advantages of being simple in structure and convenient to mount. The electric power spare parts can be stored in a classified mode during vehicle-mounted transportation, so that standardized management is achieved, the convenience for storing and taking the spare parts is improved in the site construction process, the ready time of construction is shortened, and the working efficiency is improved. Collision is further avoided between the spare parts or between the spare parts and the carriage in the transportation process, and therefore the protective property is improved.