An alignment device for a power module of a power electronic device is provided, which may be used for aligning the power module while the power module being plugging to or from a rear mounting part of a cabinet of the power electronic device. The rear mounting part is disposed at an inner side of a back plate of the cabinet, the alignment device comprises a first connector disposed on the power module; guide rail units disposed on inner sides of a left side plate and a right side plate of the cabinet; a second connector disposed on the rear mounting part; and a guide device for limiting an offset of the power module moving along the guide rail unit.