An air conditioner, comprising an indoor unit and a controller , wherein the indoor unit includes a main control board , and the main control board is communicatively connected to the controller in a wired or wireless manner; wherein the main control board is provided with an air purification identifier bit therein, the air purification identifier bit being assigned with a value according to whether an air purification module is equipped; and wherein, when the air conditioner is turned on, the controller is adapted to communicate with the main control board , the main control board is adapted to send the air purification identifier bit to the controller , and the controller is configured to perform control output according to the air purification identifier bit; and wherein in a case where the air purification identifier bit is valid, it is determined that the indoor unit is provided with the air purification module and the controller is configured to control an air purification identifier to be displayed, the air purification identifier being used to indicate a turn-on state of the air purification module ; otherwise, in case where the air purification identifier is invalid, it is determined that the indoor unit is not provided with the air purification module , and the controller is configured to control the air purification identifier not to be displayed; wherein the controller is further configured with a function selection setting identifier bit for forced control of display or non-display of the air purification identifier; wherein the function selection setting identifier bit has a higher priority than the air purification identifier bit; and wherein the controller is configured to first determine whether the function selection setting identifier bit is valid, and if the function selection setting identifier bit is valid, the controller is configured to control the air purification identifier to be displayed. wherein the main control board is provided with an air purification identifier bit therein, the air purification identifier bit being assigned with a value according to whether an air purification module is equipped; and wherein, when the air conditioner is turned on, the controller is adapted to communicate with the main control board , the main control board is adapted to send the air purification identifier bit to the controller , and the controller is configured to perform control output according to the air purification identifier bit; and wherein in a case where the air purification identifier bit is valid, it is determined that the indoor unit is provided with the air purification module and the controller is configured to control an air purification identifier to be displayed, the air purification identifier being used to indicate a turn-on state of the air purification module ; otherwise, in case where the air purification identifier is invalid, it is determined that the indoor unit is not provided with the air purification module , and the controller is configured to control the air purification identifier not to be displayed; wherein the controller is further configured with a function selection setting identifier bit for forced control of display or non-display of the air purification identifier; wherein the function selection setting identifier bit has a higher priority than the air purification identifier bit; and wherein the controller is configured to first determine whether the function selection setting identifier bit is valid, and if the function selection setting identifier bit is valid, the controller is configured to control the air purification identifier to be displayed. <EOS>