The invention provides a control method, a control device and an air conditioner, and relates to the technical field of air conditioners. The control method of the air conditioner comprises the following steps that the air conditioner is started, and an initial
operation mode of the air conditioner is recognized; whether a forced
sleep mode signal is received or not is judged; if yes, the air conditioner directly enters a
sleep mode; if not, the air conditioner operates automatic sleep judgment, wherein automatic sleep judgment comprises the substeps that the starting time t0 is obtained, whether t0 satisfies the condition that t0 is larger than or equal to t1 and smaller than or equal to (t1+
delta t1) or not is judged, if yes, the air conditioner continues to run the initial
operation mode for the duration of
delta t2 and enters the
sleep mode, if not, the air conditioner continues to run the initial
operation mode to the moment t1, then continues to run for the duration of
delta t2 and enters the sleep mode, t1 is a set sleep start moment, delta t1 is a set
sleep duration, and when the air conditioner runs the sleep mode, the rotating speed of an inner fan is reduced. The operation mode of the air conditioner better accords with work and rest habits of the
human body, and the comfort of users is improved.