A method for mounting an air outlet structure of an air conditioner, comprising the steps of: determining whether the supporting strength of a mounting base satisfies the ceiling requirements of the air outlet structure of the air conditioner; mounting a lateral surface of the air outlet structure of the air conditioner on the mounting base and mounting the air outlet structure of the air conditioner on an indoor unit of the air conditioner if the requirements are satisfied, so that the mounting base provides a main support for the air outlet structure of the air conditioner, and the indoor unit provides an auxiliary support for the air outlet structure of the air conditioner; mounting the air outlet structure of the air conditioner on the indoor unit and mounting a lateral surface of the air outlet structure of the air conditioner on the mounting base if the requirements are not satisfied, so that the mounting base provides an auxiliary support for the air outlet structure of the air conditioner and the indoor unit provides a main support for the air outlet structure of the air conditioner; characterized in that the step of mounting a lateral surface of the air outlet structure of the air conditioner on the mounting base comprises the following steps: mounting a fixing member on the lateral surface of the air outlet structure of the air conditioner; wherein the fixing member comprises a first opening and a second opening, and at least one of the first opening and the second opening is an oblong hole; the fixing member is fixed to the lateral surface of the air outlet structure of the air conditioner through the first opening; and fixing the air outlet structure of the air conditioner with the mounting base by passing a fastener through the second opening. determining whether the supporting strength of a mounting base satisfies the ceiling requirements of the air outlet structure of the air conditioner; mounting a lateral surface of the air outlet structure of the air conditioner on the mounting base and mounting the air outlet structure of the air conditioner on an indoor unit of the air conditioner if the requirements are satisfied, so that the mounting base provides a main support for the air outlet structure of the air conditioner, and the indoor unit provides an auxiliary support for the air outlet structure of the air conditioner; mounting the air outlet structure of the air conditioner on the indoor unit and mounting a lateral surface of the air outlet structure of the air conditioner on the mounting base if the requirements are not satisfied, so that the mounting base provides an auxiliary support for the air outlet structure of the air conditioner and the indoor unit provides a main support for the air outlet structure of the air conditioner; characterized in that the step of mounting a lateral surface of the air outlet structure of the air conditioner on the mounting base comprises the following steps: mounting a fixing member on the lateral surface of the air outlet structure of the air conditioner; wherein the fixing member comprises a first opening and a second opening, and at least one of the first opening and the second opening is an oblong hole; the fixing member is fixed to the lateral surface of the air outlet structure of the air conditioner through the first opening; and fixing the air outlet structure of the air conditioner with the mounting base by passing a fastener through the second opening.