Abstract.There is a kind of multi-channel automatic switch high precision low voltage switch. The conversion axis of low potential automatic change-over switch has public contact. The public contact and indexing plate’s each indexing position contact constitute the multi-channel change-over switch. Stepper motor driver connects conversion axis. The control of stepper motor includes stepping motor drive and control department. The control department includes pulse output unit, PCI-1716 series data acquisition card and output connecting stepper motor drive’s drive unit. The one digital output terminal of PCI-1716 series data acquisition card is motor direction control terminal which connects to the one drive channel inputs of drive unit; the other digital output terminal of PCI-1716 series data acquisition card is bearing drive unit start signal which connects to drive unit. Ensure the parasitic potential of multi-channel automatic transfer switch is not more than 1μV. Realize the multi-channel thermocouple data automatic measurement when testing the industrial thermocouple.