The embodiment of the invention provides an initial positioning device of a permanent magnet synchronous motor, which comprises an inverter, wherein a switching tube of an A-phase upper bridge arm, a switching tube of a B-phase lower bridge arm and a switching tube of a C-phase lower bridge arm of the inverter are conducted with each other, a switching tube of an A-phase lower bridge arm, a switching tube of a B-phase upper bridge arm and a switching tube of a C-phase upper bridge of the inverter are disconnected with each other, an A-phase output point of the inverter is connected with the head end of a B-phase stator winding of the permanent magnet synchronous motor, a B-phase output point of the inverter is connected with the head end of the B-phase stator winding of the permanent magnet synchronous motor, and a C-phase output point of the inverter is connected with the head end of the C-phase stator winding of the permanent magnet synchronous motor. Resistivity of a divider resistance is larger than or equal to the difference between the quotient of minimum voltage output by the inverter when the inverter outputs current needed by the initial positioning divided by the current needed by the initial poisoning, and equivalent resistance of a three-phase stator winding of the permanent magnet synchronous motor.