The invention discloses an auxiliary device for connecting wire poles with cross arms. The auxiliary device comprises an annular support seat, an annular fixing seat and oblique stay rods. The lower surface of the annular support seat is fixedly connected with the upper surface of the annular fixing seat by the oblique stay rods, a plurality of threaded through holes A are uniformly formed in the upper surface of the annular support seat in the circumferential direction, and a plurality of threaded through holes B are peripherally uniformly formed in the circumferential side surface of the annular fixing seat. The auxiliary device has the advantages that the annular fixing seat can sleeve the wire poles when the auxiliary device is used, the threaded through holes B and threaded through holes C in the annular fixing seat correspond to mounting holes in the wire poles, then the annular fixing seat is fastened and connected with the wire poles by high-strength bolts, and then the cross arms can be connected to the upper surface of the annular support seat by bolts according to actual requirements, so that the cross arms and the wire poles can be safely and reliably connected with one another by the auxiliary device, and the auxiliary device is easy to operate and can be used for connecting the multiple cross arms in different directions with the wire poles.