The invention discloses a horizontal single-connection insulator string detection robot system. The horizontal single-connection insulator string detection robot system comprises an insulator electrification detector, caterpillar mechanisms symmetrically arranged and connected above a horizontal single-connection insulator, and encircling mechanisms symmetrically arranged and connected below a horizontal single-connection insulator. The caterpillar mechanisms and the encircling mechanisms are connected to form a ring unit encircling the horizontal single-connection insulator. The encircling mechanism under the insulator is provided with a main control box which is used for lowering the center of gravity of the robot and preventing the deflection of the robot, and a controller is arranged in the main control box controlling the caterpillar mechanisms to move on the horizontal single-connection insulator through a line. The insulator electrification detector sends the detected data to a control center through a wireless data transmission module. The horizontal single-connection insulator string detection robot system has the advantages of being simple in principle, reasonable in structure, easy to operate, good in safety, less abrasion on insulator, wide in using range and capable of adapting to electrification detection operations of horizontal single-connection and double-connection insulator strings.