The invention provides a power transmission line insulator detection robot, which comprises a fixation installation support, a walk driving device, a guide device and a detection device. One side of the fixation installation support is an insulated toothed bar. The walk driving device is engaged with the insulated toothed bar through a gear. The guide device is arranged on the walk driving device.The detection device is fixedly connected to one side of the walk driving device. In the process of detecting an insulator string of a power transmission line, the walk driving device moves based onengagement between the gear and the toothed bar, and after the detection device reaches a preset position, a probe is rotated to lap each steel cap to realize detection of the insulator string one byone.