The invention discloses a method for establishing a car model for car washing. A transmission device, an ultrasonic sensor and laser sensors are included. The method comprises the following steps that the laser sensors are arranged on the upper portion and the two sides of the transmission device, and the ultrasonic sensor is arranged on the surfaces of the transmission device; when a to-be-washed car is parked on the transmission device, the transmission device, the ultrasonic sensor and the laser sensors start to work; the car model is established according to detection results of the ultrasonic sensor and the laser sensors; and the collected car model is matched with the license plate number of the car and stored. The to-be-washed car is parked on the transmission device, so that the transmission device passes through a detection device composed of the ultrasonic sensor and the laser sensors in a reciprocating mode to conduct model establishing on the car. The method has the advantages that a washing device is controlled to work according to the shape of the car, so that the car is not prone to being worn; and the car model can be obtained in a direct reconstruction mode through existing equipment, and the improved cost is low.