Two-stage clamping and sealing assembly and filling head using same

The utility model relates to the technical field of automobile fluid filling, and discloses a two-stage clamping and sealing assembly and a filling head using the assembly, the two-stage clamping and sealing assembly comprises a movable piston and a static piston which are installed on a piston rod, the movable piston comprises a first-stage movable piston and a second-stage movable piston, and the extending end of the first-stage movable piston is connected with the upper end face of the second-stage movable piston. The static piston is located between the first-stage movable piston and the second-stage movable piston. A first-stage clamping cavity is formed among the first-stage movable piston, the shell and the piston rod, and a first-stage loosening cavity is formed among the first-stage movable piston, the static piston and the piston rod; a second-stage clamping cavity is formed between the second-stage movable piston and the static piston, and a second-stage loosening cavity is formed between the secon