The invention discloses a self-cleaning control method of a fixed frequency air conditioner, and belongs to the technical field of air conditioning regulation. The self-cleaning control method includes the steps that whether the fixed frequency air conditioner can enter into a self-cleaning mode or not is determined; the self-cleaning mode is performed according to the sequence of condensation, frosting, defrosting and exiting; and the fixed frequency air conditioner does not change the rotation speed of a compressor, and performs the self-cleaning mode by controlling start and stop of the compressor of the fixed frequency air conditioner, the rotation speed of an internal fan, the start and stop of an external fan, the state of an air deflector and a four-way valve. The self-cleaning control method overcomes the disadvantage that the rotation speed of the compressor of the fixed frequency air conditioner is not adjustable, the self-cleaning function of an evaporator of the fixed frequency (the rotation speed of the compressor is not adjustable) air conditioner is realized, the safe operation of an air conditioning system is ensured, the safe operation of the system and the effectof self-cleaning are taken into account, and market prospects are achieved.