Automatic Trailer and Container Internal Washing System is for efficiently washing and optinally disinfection for inside of any closed trailers, containers and similar equipment. The robot sprays the smoothing detergent spreading inside the surface at its first move to the end of the trailer. On the return move all the pre-smoothened surface is washed with high pressure water and the dirty water is swept out again with high pressure water sprayed from the special nozzles under the robot. This action is fully automatical but also under the control of an operator and takes a little time.