The invention discloses a trench gate power device manufacturing method, and the method comprises the steps: forming a hard mask layer, carrying out the photoetching and forming a trench; carrying out the self-aligning channel injection with an inclination angle; continuing the etching of a semiconductor substrate at the bottom of a trench, so as to remove the channel injection impurities on the surface of the bottom of the trench; forming a gate medium layer and a polysilicon gate; adding an opening of the hard mask layer, and carrying out the self-aligning source injection; removing the hard mask layer; carrying out the complete body region injection; forming a contact injection layer with the depth being less than the depth of a source region, and forming an interlayer film and a contact hole; carrying out the self-aligning contact injection formation after the contact injection layer is formed through complete contact injection before the interlayer film is formed or after the etching of the contact hole; placing metal in the contact hole, and forming ohmic contact with the contact injection layer. The invention also discloses a trench gate power device. The method can prevent the contact hole from passing through a source region, can improve the stability of a threshold voltage of the device, can reduce the size of a device unit, and can reduce the conduction resistance.