The invention provides a wall-mounted air conditioner indoor unit. The air conditioner indoor unit comprises a shell body, a heat exchanger, an air injection part, a first air supply assembly and a second air supply assembly, wherein the shell body is provided with a housing and a front panel, air inlets are formed in the top wall of the housing, and a long circular air supply opening is formed inthe lower portion of the front panel; the heat exchanger comprises a first heat exchange section and a second heat exchange section, wherein the first heat exchange section is arranged at the position close to the front panel, and the second heat exchange section is arranged at the position tightly close to the top wall of the housing; the air injection part is arranged in the air supply openingand is used for spraying internal heat exchange airflow forwards and driving environment air to be sent out forwards; and the first air supply assembly and the second air supply assembly are transversely arranged at the rear lower part of the heat exchanger at intervals, and are correspondingly used for generating the heat exchange airflow which enters the shell body from the air inlets at the topand is supplied in from one side of the air injection part after exchanging heat with the first heat exchange section and the second heat exchange section in sequence. According to the wall-mounted air conditioner indoor unit, the air supply amount is increased, and the indoor temperature is reduced uniformly in an overall mode.