The invention discloses a dam filling water adding vehicle cleaning system. A pit is dug in a driving road, the pit is supported by a steel pipe, one side of the driving road is provided with a sedimentation tank, one side of the sedimentation tank communicates with the pit, and the other side of the sedimentation tank is provided with an overflow hole; the pit are provided with stand columns, andthe stand columns are arranged on the two sides of the pit; the system further comprises a water supply system, wherein the water supply system particularly comprises a submersible electric pump, a water supply pipeline and a water spraying pipeline; one end of the water supply pipeline is connected with the submersible electric pump, the other end of the water supply pipeline is connected with the water spraying pipeline, and the water spraying pipeline is provided with water spraying openings; and the water spraying pipeline is divided into an upper pipeline and a lower pipeline, the upperpipeline is erected at the top ends of the stand columns, the lower pipeline is connected to the lower part of the steel pipe, and the water spraying openings of the upper pipeline and the lower pipeline are opposite up and down. The upper pipeline is used for adding water in the air, a vehicle drives slowly during water adding, and when the vehicle passes the vehicle length distance, all water isdirectly sprayed into the whole compartment; and the lower pipeline is adopted for flushing flowing sewage and purifying the vehicle.