The invention discloses a full-automatic nucleic acid extraction machine which comprises a machine body, a workbench, a swing mechanism, a suction-injection gun head, a pressurization gun, a transmission mechanism and a controller, wherein the machine body at least comprises a rack; a test tube placing hole position, a suction nozzle placing hole position, a filter hole position, a cracking hole position, a finished product collection hole position and a waste suction nozzle recycling slot are formed in the workbench; the swing mechanism is used for driving the workbench to reciprocate relative to the rack; an opening at the upper end part of the suction-injection gun head is connected with an injection pump, and the lower end part is matched with a suction nozzle; an opening at the upper end part of the pressurization gun is communicated with a pressurization device, and an air outlet is formed in the lower end part; the transmission mechanism is used for driving the suction-injection gun head and the pressurization gun to move along the length direction and height direction of the machine body; and the controller is used for controlling the transmission mechanism and the swing mechanism. The nucleic acid extraction machine disclosed by the invention can realize automatic suction and injection of samples and reagents, thus improving the working efficiency; and moreover, during filtration, positive pressure is applied to a filtering tubular column by the pressurization gun, the filtering time is shortened, and the nucleic acid extraction efficiency is further improved.