The invention provides a multifunctional bird repeller for preventing birds from building bird nests on a telegraph pole. The multifunctional bird repeller comprises an upper fixing part, a lower fixing part, a fixing bolt, an installation block and thorns; the right side of the bottom of the upper fixing part is connected with the right side of the top of the lower fixing part in a hinged mode, the lower fixing part is provided with the fixing bolt, the upper fixing part is provided with a nut, and after a cross arm is arranged between the upper fixing part and the lower fixing part, locking of the cross arm, the upper fixing part and the lower fixing part is achieved through cooperation of the fixing bolt and the nut; the hemispherical installation block is fixed to the top of the upper fixing part, the circular arc surface of the installation block is a mirror surface, a plurality of double-screw bolts are arranged on the circular arc surface of the installation block, and the thorns are installed on the double-screw bolts; the side faces of the upper fixing part are provided with solar cell panels, and the inner side of the installation block is provided with a buzzer. According to the multifunctional bird repeller, after a bird harm prevention spacer is installed on the cross arm, the condition that the birds fall on the cross arm to build the bird nests can be effectively prevented through arrangement of the thorns.