In order to realize the automatic detection of zero value insulator in power transmission line, based on the demand analysis of insulator detection application in Extra-high Voltage (EHV) transmission line, designing and developing a kind of insulator detection robot based on STM32 which can climb EHV horizontal and vertical insulator strings with the EHV line background. Emphatically the system design, mechanical structure design and field test of robot were introduced. It is achieved of EHV transmission line insulator of zero value automatic detection based on STM32 as core data processor.