The invention discloses a flange plate drilling device on a wind power spindle. The flange plate drilling device comprises laser heads arranged on a ring piece along a ring array, and the quantity andthe mounting positions of the laser heads are matched with the quantity and the positions of holes to be processed in a flange plate. The ring piece is arranged on a stand column of a laser-beam drilling machine through a connecting piece in a sliding mode, positioning holes are formed in the stand column, and positioning pins matched with the positioning holes are arranged and are used for fixing the ring piece of which the position is adjusted. The flange plate drilling device changes the condition that when being drilled in the past, a shaft end flange needs to be lifted by a crane and then is drilled. The flange plate drilling device improves the efficiency and does not occupy the crane. The flange plate drilling device can drill holes in one step through a circle of laser heads on the ring pieces, and the efficiency is greatly improved. a hydraulic slewing gear improves the surface smoothness of hole wall of laser drilling.