A rolling piston installed between a piston and a cylinder includes: a plurality of balls, wherein the balls are connected end to end to form the rolling piston ring, and a quantity of the balls is no less than three; or comprising: a plurality of columns, wherein the columns are connected end to end to form the rolling piston ring, and a quantity of the balls is no less than three; or comprising: balls and columns, wherein the balls and the columns are connected end to end to form the rolling piston ring, and a total quantity of the balls and the columns is no less than three; wherein both the balls and the columns are extendable, and/or a recess on the piston for installing the rolling piston ring is extendable and a slide on the cylinder for installing the rolling piston ring is extendable.