The invention discloses a control method of an air conditioner. The control method of the air conditioner comprises the following steps: when the air conditioner enters a preset sleep operation mode, a temperature value obtained through detection according to a preset temperature regulation parameter and a preset standard sleep parameter curve are acquired, and a correction value to the standard sleep parameter curve is determined according to the detected temperature value; according to a difference value between the currently detected temperature value and the preset standard temperature, a correction proportion of the correction value is determined; and according to the correction value and the correction proportion, a setting temperature value of the standard sleep parameter curve is regulated. The invention further discloses the air conditioner and a control device thereof. Temperature over-regulation caused by higher correction amount is avoided, and the environmental comfort is improved.