The invention discloses an inverter outputting voltage testing circuit, which comprises a U, V, W three-phase outputting voltage end and a VU, VW voltage testing end which can realize the three-phase outputting voltage, and also comprises a first to a sixth dividing potential electric resistances (R11, R12, R13, R2, R31, R32), a first to a third filter capacitors (C11, C12, C13), and a first and a second voltage comparers (U1, U2), which are connected between the U, V, W three-phase outputting voltage end and the VU, VW voltage testing end. The invention minimizes number of megohm-grade electrodes to 2/3 of original number through promoting existing technique under a condition that current circuit performance can be affected, which lowers cost, simplifies three-phase outputting voltage differential testing circuit, decreases products volumes, lowers products cost, and simultaneously increases products competitive power.