The invention discloses a defrosting control method for an air conditioner. The defrosting control method includes the steps that when the air conditioner enters a defrosting mode, outdoor environment temperature and outdoor environment humidity are obtained; whether the outdoor environment temperature and the outdoor environment humidity meet preset conditions is judged; if yes, an outdoor fan is controlled to rotate reversely according to the pipe temperature and defrosting time of an outdoor heat exchanger so that defrosting can be performed on an enclosure net cover of the outdoor heat exchanger. According to the control method, residual frost on the enclosure net cover of the outdoor heat exchanger can be effectively cleared away. The invention further discloses a defrosting control device for the air conditioner.