With the continuous economic development and the rapid advancement of urbanization, the stable operation of distribution networks has become a key factor in ensuring the reliability of power systems. In response to the problems of high risk, high labor intensity, and low efficiency in distribution network operations, this paper designs an auxiliary operation mechanical arm for distribution networks. This auxiliary operation mechanical arm is fixed on the working bucket of an insulated boom truck. The main body is a two-degree- of-freedom SCARA mechanical arm that moves in a plane, and the end is connected to a three-degree-of-freedom end effector through a flange to cooperate in completing the pitch, deflection, axial feed, and clamping of insulated rods, achieving coarse positioning in the plane and precise positioning of the target. The auxiliary mechanical arm operation platform adopts a fully insulated design. The platform is made of glass nylon material, and the edges are rounded. According to ergonomics, the installation position of the mechanical arm is arranged according to an average height of 1.75m, and the operation plane is at 1.5m, which is convenient for operators to perform operations. The D-H coordinate system of the auxiliary mechanical arm is established, and the kinematic model of the mechanical arm is established using the D-H parameter method. Based on the Monte Carlo method, the reachable workspace of the end is obtained in MATLAB simulation. The XY projection continuously presents an elliptical shape, and the size is consistent with the 0.8m arm span. The point cloud projections on the XZ and YZ planes present a narrow band shape distributed along the nominal height. Its three-dimensional spatial structure is approximately a flat ellipsoid and shows good structural continuity. The finite element analysis of the load-bearing platform and the key end components shows that the strength and stiffness meet the design requirements. Through multi-loop servo control with force feedback and feedforward compensation, the end can achieve controllable contact and micro-operation, enhancing the stability of the auxiliary operation system. Under the force-assisted control (force feedback and feedforward compensation), this auxiliary mechanical arm can accurately and stably achieve controllable contact at the end and target alignment, completing typical assembly/replacement operations using the short-pole method, and has good universality and engineering application value.