The invention provides a defrosting control method, a defrosting control device and an air conditioner. The defrosting control method is used for the air conditioner. The air conditioner comprises a compressor and an outdoor heat exchanger which communicate with each other through a pipeline. The defrosting control method comprises the steps that when it is detected that the pipeline enables the compressor and the outdoor heat exchanger to communicate in a defrosting manner, the environmental temperatures, the middle temperatures and the outlet temperatures of the outdoor heat exchanger are recorded in real time; according to the operation state of the compressor and/or the operation duration of the defrosting mode, the defrosting mode is controlled to be ended; and/or when the environmental temperature is lower than or equal to a preset environmental temperature, according to the middle temperature and the outlet temperature, the defrosting mode is controlled to be ended. By the adoption of the defrosting control method, the defrosting control device and the air conditioner, the frequency of the situation that the defrosting mode is ended when defrosting is incomplete can be reduced, the frequency of the situation that defrosting is continuously conducted when no frost exists can also be reduced, the energy efficiency and reliability of the defrosting mode are further improved, and the defrosting control method and the defrosting control device are particularly suitable for defrosting outdoor heat exchangers in adverse low-temperature environments.