The invention provides a floating type low-friction air cylinder with a sealing ring. The air cylinder comprises a front cover, a rear cover, a cylinder barrel, a piston rod and a piston, the front cover, the cylinder barrel and the rear cover are connected in sequence, the piston rod penetrates through the front cover, and is partially arranged in the cylinder barrel, the piston is arranged in the cylinder barrel and is connected with the piston rod, the air cylinder further comprises one sealing ring and one piston sealing ring groove, wherein the piston sealing ring groove is an annular groove body located on the piston, the section of the piston sealing ring groove is in a Y shape, the section of the sealing ring is in a Y shape, the radial outer surface of the sealing ring is an arc-shaped sealing portion which protrudes outwards, the linear portion of the Y shape of the sealing ring comprises several protrusion sealing portions which axially symmetrically protrude, the sealing ring is sleeved with the piston sealing ring groove, and the inner ring of the sealing ring is not in contact with the groove bottom of the piston sealing ring groove. According to the air cylinder, thepressure of the sealing ring on the cylinder barrel is only generated by the sealing ring material forming supporting force, and the pressure of the sealing ring on sealing of the bottom of the piston sealing ring groove is avoided, so that the pressure is small, and the movement is fast.