The invention provides a control method and system for an air-conditioner, an air-conditioner and a remote controller of an air-conditioner. The control method for the air-conditioner comprises the steps of recording a set of operating parameters of the air-conditioner set by a user within a preset period of time after the air-conditioner is started every time an air-conditioner starting instruction given by the user is received, so that a plurality of sets of operating parameters set by the user are obtained after the air-conditioner is started multiple times; selecting the set of operating parameters, which appear most frequently, from the multiple sets of operating parameters to serve as the operating parameters, corresponding to the current started state, of the air-conditioner, so that the air-conditioner works according to the operating parameters. By the adoption of the scheme, the default operating parameter, corresponding to the current started state, of the air-conditioner can better accord with the using habits of the user, the user does not need to reset the operating parameters of the air-conditioner every time the air-conditioner is started, operation processes are simplified for the user, and using experience of the user is improved.