The invention relates to an undervoltage tripping device suitable for a three-phase supply. The device comprises an electromagnet coil, an armature, a rectifier circuit, a sampling circuit, a line voltage detection module and a main control module, wherein the current input end of the electromagnet coil is connected with the output end of the rectifier circuit, the current output end is connected with a switching circuit; the armature is controlled by the electromagnet coil, the input end of the rectifier circuit is connected with any line voltage in the three-phase supply, the sampling circuit is used for detecting the output voltage of the rectifier circuit, the line voltage detection module is arranged at the output end of the three-phase supply and used for detecting at least two groups of line voltages; and a nominal voltage Ue, a strong starting voltage value and a voltage value for maintaining the pickup of the armature are stored in the main control module. The switching circuit is controlled to connect if the effective value of the line voltage satisfies 80% of the nominal voltage Ue and the strong starting voltage value; and the switching circuit is controlled to disconnect if any line voltage is lower than 50% of the nominal voltage Ue or the sampling voltage is not equal to the voltage value for maintaining the pickup of the armature.