The invention discloses a testing device used for triggering detection of a thyristor in a UPFC (Unified Power Flow Controller) converter valve sub-module. The testing device comprises a detection circuit, a charging/discharging circuit and a controller, wherein the detection circuit comprises a current transformer and an electric reactor which are connected in series; the current transformer is connected with a signal input end of the controller; the charging/discharging circuit comprises a direct-current power supply and a discharging resistor which are connected in parallel; a branch circuit of the discharging resistor is connected with a switch K2 in series; a branch circuit of the direct-current power supply is connected with a switch K1 in series; and a signal output end of the controller, the two ends of the detection circuit and the two ends of the charging/discharging circuit are used as external ports of the testing device. According to the testing device, testing equipment is simplified while testing requirements on a triggering test of the thyristor of a UPFC converter valve are met; and a testing result is very intuitive and the efficiency is improved.