The plastic deformation of the head of the strain-strengthened 304L pressure vessel includes: the plastic deformation produced during the production of the head and the plastic deformation of the head during the strain strengthening process. When people perform strain strengthening of pressure vessels, they often ignore the plastic deformation of the head during production, and the production of the head will produce a large amount of plastic deformation, which can reach up to about 40%. The plastic deformation of different parts of the head is different. The most intuitive manifestation is that the wall thickness is different at all parts of the head. The wall thickness is the thinnest at the small arc, the wall thickness is the thickest at the straight side section, and at the same time in the entire large arc. The wall thickness of part of the head is also constantly changing, and the wall thickness in the top area of the head is smaller. Due to the large plastic deformation of the formed head, the mechanical properties of the head are affected to a certain extent. 304L will have a certain degree of work hardening when plastic deformation occurs, and the yield strength of the material has been improved.