Disclosed is an ultrasonic cleaning method for complex pipe fittings. The complex pipe fittings such as bellows and metal hoses are widely applied to the aerospace field. According to the ultrasonic cleaning method for the complex pipe fittings, the ultrasonic method is applied to the cleaning of the bellows and the metal hoses. Ultrasonic cleaning which is physical cleaning is environmentally friendly. The ultrasonic cleaning can be combination cleaning if proper cleaning agents are added to the cleaning liquid and good cleaning effects can be achieved. The best cleaning agent formulation is finally obtained by adding various cleaning agents to an ultrasonic cleaning tank for testing and comparing the cleaning effects.