The utility model discloses an automatic matching device for composite alcohol diesel oil. The automatic matching device is composed of a cleaning tank, a diesel oil tank, a plurality of alcohol storing tanks, an alcohol collecting tank, a measuring and controlling platform, an agitator, a cosolvent tank, a radiating device, a composite alcohol diesel oil storing tank and a composite alcohol diesel oil collecting tank. The cleaning tank is connected with the diesel oil tank, the alcohol storing tanks and the agitator. The diesel oil tank is connected with a diesel oil injection pipeline and a diesel oil output pipeline, an eighth electromagnetic valve and a first flow meter are arranged on the diesel oil output pipeline, and the alcohol storing tanks are connected with alcohol injection pipelines and alcohol output pipelines. Electromagnetic valves and flow meters are arranged on the alcohol output pipelines, and the agitator is connected with the cosolvent tank through a pipeline. The automatic matching device has the advantages that the personal error in the matching process is effectively avoided while labor work is reduced, and the production efficiency of finished products is greatly improved.