The invention discloses a drill stem thread centering device for an automatic drilling machine and a centering control method. By means of the drill stem thread centering device and the centering control method, a driving drill stem and a to-be-connected drill stem thread are automatically centered in real time according to the actual deviation conditions in the drill stem connecting and bucklingprocess, and therefore the aims of relieving the abrasion to thread connectors and prolonging the service life of the drill stem are realized; moreover, each time of adjustment is made according to the actual deviation conditions of the photographed to-be-connected drill stem, and the effectiveness and success rate of thread centering are better ensured.