The invention provides a control method for an air conditioner, the air conditioner, a control method for a mobile terminal, the mobile terminal and a control system. The control method for the air conditioner comprises the steps that the relative position information, from the mobile terminal, of an indoor target article and the air conditioner is received, the temperature distribution detection range is determined according to the relative position information, a thermal image within the temperature distribution detection range and the thermal high-temperature area in the thermal image are obtained, whether the thermal high-temperature area is larger than or equal to a preset thermal high-temperature threshold value or not is judged, and whether the air conditioner needs to be controlled and/or a user is reminded is determined according to a judgment result. According to the technical scheme, the relative positions of a bed and the air conditioner can be set flexibly through the mobile terminal, so that a quilt kicking detection range and a judgment threshold value are determined, and thus the accuracy of quilt kicking detection during sleeping of a user can be improved; meanwhile, error recognition can be reduced, and thus user experience is improved.