The invention provides an axial flow fan blade, an axial flow fan and an air conditioner. The axial flow fan blade comprises a plurality of blades and a hub, the plurality of blades are arranged at intervals in the circumferential direction of the hub, each blade comprises a front edge, an outer edge, a rear edge and an inner edge, and each rear edge comprises a connecting line AB, a connecting line BE, a connecting line EC and a connecting line CD which are sequentially connected end to end. A plane passing through the rotating axis of the blade is set as a first plane, and the blade is circumferentially projected to the first plane in the rotating direction of the blade to form a first contour line. On the first contour line, a point A, a point B and a point C are located on a same straight line L1, and the included angle theta 1 is formed between the straight line L1 and the rotating axis of the blade and is larger than or equal to 75 degrees and smaller than or equal to 120 degrees; and the projection of the connecting line EC is a line segment, the line segment is located on a straight line L2, and the included angle between L2 and L1 is theta 2, and theta 2 is larger than 0 degree and smaller than or equal to 30 degrees. According to the axial flow fan blade, turbulence of the tail edge of the axial flow fan blade can be improved and reduced, aerodynamic noise of the fanblade can be reduced, and the efficiency of the fan can be improved.