The invention discloses a floating type piston rod air-liquid damping air cylinder which comprises a cover sleeve, a cylinder cover, a first cylinder body, a second cylinder body and a piston rod; the first cylinder body is internally provided with a first piston; the second cylinder body is internally provided with a second piston; a hydraulic oil chamber is formed between the first piston and the second piston; a hydraulic oil damping hole is formed between the first cylinder body and the second cylinder body; the first piston is internally provided with a cavity; the lower end of the first piston is connected with a screwed plug; and a bolt connected with the piston rod is arranged in the cavity in a floating manner. With the adoption of a floating type piston rod technology, the problem that the component processing and assembly cost is high under high precision condition is solved; with the adoption of an air-liquid matching mode which adopts compressed gas to provide a driving force and hydraulic oil to provide a damping force, gentle extension and contraction of the piston rod are ensured; and the floating type piston rod air-liquid damping air cylinder is safe and reliable to use.