<p>An air conditioner indoor unit comprising: a housing (1); an impeller (2) arranged in the housing and forming a cross flow fan; a rear side plate (4) arranged downstream the impeller and forming a rear side of a diffused air path (3); a front side plate (5) forming a front side of the diffused air path and including a first air outlet surface (9), a second air outlet surface (11) and a third air outlet surface (12); the first air outlet surface arranged near to the impeller and having a portion on a side of an air outlet (6) of the diffused air path slanted in a direction away from a reference surface (10) defined by the rear side plate; the second air outlet surface arranged next to the first air outlet surface on the side of the air outlet (6) and having a portion on the side of the air outlet slanted in a direction away from the reference surface; and the third air outlet surface arranged next to the second air outlet surface on the side of the air outlet end and having a portion on the side of the air outlet slanted at 20 DEG - 30 DEG in the direction away from the reference surface. <IMAGE></p>
