The invention relates to a double permanent magnet synchronous motor control inverter and a compensation control method. The double permanent magnet synchronous motor control inverter includes a controller, three-phase permanent magnet motors M1 and M2, inverter bridge arms L1, L2, L4 and L5 all connected in parallel to a common DC power supply, and a capacitor bridge arm L3. A first phase windingof the M1 is connected to a midpoint of the L1; a second phase winding of M1 is connected to a midpoint of the L2; a third phase winding of the M1 is connected to a midpoint of the L3; a first phasewinding of the M2 is connected to a midpoint of the L3; a second phase winding of the M2 is connected to a midpoint of the L4; and a third phase winding of the M2 is connected to a midpoint of the L5.According to the double permanent magnet synchronous motor control inverter and the compensation control method, charging circuits of DC bus capacitors are increased, so that after it is detected that the unbalance of the two capacitor voltages exceeds a certain threshold value, a redundant bridge arm circuit charges the corresponding capacitor, so that the midpoint of the potential moves in thedirection of balance. The offset of the midpoint of the potential is clamped within a certain range, suppressing the voltage imbalance of the two series capacitors on a DC bus.