The utility model discloses an intelligent fuel oil return detection controller of a diesel locomotive. The intelligent fuel oil return detection controller consists of a controller box body, a fuel oil filter, a central electronic controller, a pipeline for being connected with a fuel oil tank, a pipeline for being connected with a contaminated-oil basin and a pipeline for being connected with a contaminated-oil tank, wherein the center of the controller box body is provided with a center oil passage, the top end of the center oil passage is provided with an electromagnetic push rod cleaner, the periphery of the middle part of the center oil passage is provided with a protective window and a sensor, the lower part of the center oil passage is provided with the pipeline for being connected with the fuel oil tank and the pipeline for being connected with the contaminated-oil tank to be connected with the fuel oil tank and the contaminated-oil tank respectively, the bottom of the center oil passage is provided with the pipeline for being connected with the contaminated-oil basin, the filter is arranged outside the controller box body, a filter net is arranged in the filter, the top of the filter is provided with an oil inlet pipe to be connected with a fuel oil return header pipe of a fuel injector, the side face of the filter is provided with an oil conveying pipe to be connected with a center oil pipe, and the central electronic controller is connected with the sensor through a lead wire. The controller has the effects of energy conservation and environment protection, is simple in operation, accurate and reliable in detection control and low in cost, has wide applicability and is easily popularized in railway transportation.