The invention discloses a whole-set secondary circuit polarity testing device used for relay protection. The whole-set secondary circuit polarity testing device comprises a signal generation module and a monitoring module. The signal generation module comprises a power supply module and a signal output module. The power supply module comprises a built-in rechargeable battery E[internal], a battery capacity display circuit and a power supply indication circuit. The built-in rechargeable battery E[internal] conducts charging through a connection plug external adapter. The signal output module comprises a relay, a switch-on control switch and a two-stage overvoltage protector. The monitoring module comprises a pointer type millivoltmeter, a range switching switch and a three-stage overvoltage protector. The miniaturized and portable design is adopted, the whole-set secondary circuit polarity testing device is safe and reliable, a combined in-situ testing device and a separated remote type testing device are adopted, the whole-set secondary circuit polarity testing device is suitable for various places, it is ensured that the whole-set secondary circuit polarity testing device can be instantly available for workers, functions are perfect, and the work efficiency is greatly improved.