The embodiment of the invention provides a control method and device for delaying frosting of an air-conditioner and an air-conditioner. According to the method, low pressure and outdoor evaporator inlet temperature are obtained every preset time intervals; according to the obtained low pressure and the outdoor evaporator inlet temperature, whether the air-conditioner frosts or not is determined;and when the air-conditioner frosts, whether a compressor has enough reliability or not is determined according to the exhausting superheat degree. When the compressor has the enough reliability, thecompressor is controlled to reduce the working frequency, meanwhile, the opening degree of an expansion valve is increased to prevent frosting from aggravating, an outdoor fan does not need to reverseand defrost, while it is ensured that the exhausting superheat degree is enough, the reliability of a pressing machine is not influenced, frosting is prevented from aggravating more and more, and useexperience of users is improved.