An air stop sheet of a piston of a cylinder, the piston being accommodated in a compressor, and an air stop sheet being accommodated on a plane of a top of the head of the piston, the air stop sheet including a bending section, wherein the bending section has a positioning zone arranged on a first side thereof and located on the plane of the top of the head, and the bending section further has an acting zone arranged on a second side thereof and configured to close an air channel of the piston, wherein the bending section is a boundary line of the acting zone and the positioning zone of the air stop sheet so that a positive surface of the air stop sheet forms an obtuse angle less than 180 degrees, and a back surface of the acting zone of the air stop sheet backing the top of the cylinder turns on relative to the plane of the top of the head at an open angle θ, thus producing an air flowing space; wherein a piston rod extends downward from the head and includes an air conduit defined on a top of the piston rod and communicating with the air channel, when the piston of the air compressor stops, the acting zone of the air stop sheet turns on relative to the air channel and the air conduit, wherein the bending section of the air stop sheet has at least one collapsible guide line, and a number of the at least one collapsible guide line is determined based on an output power of the air compressor; characterized in that the bending section has a first collapsible guide line, a second collapsible guide line, and a third collapsible guide line, hence when the piston stops, the acting zone of the air stop sheet turns on relative to the plane of the top of the head at the open angle θ, or characterized in that the bending section has a first collapsible guide line and a second collapsible guide line, wherein the acting zone has a height different from a height of the positioning zone. the bending section has a positioning zone arranged on a first side thereof and located on the plane of the top of the head, and the bending section further has an acting zone arranged on a second side thereof and configured to close an air channel of the piston, wherein the bending section is a boundary line of the acting zone and the positioning zone of the air stop sheet so that a positive surface of the air stop sheet forms an obtuse angle less than 180 degrees, and a back surface of the acting zone of the air stop sheet backing the top of the cylinder turns on relative to the plane of the top of the head at an open angle θ, thus producing an air flowing space; wherein a piston rod extends downward from the head and includes an air conduit defined on a top of the piston rod and communicating with the air channel, when the piston of the air compressor stops, the acting zone of the air stop sheet turns on relative to the air channel and the air conduit, wherein the bending section of the air stop sheet has at least one collapsible guide line, and a number of the at least one collapsible guide line is determined based on an output power of the air compressor; characterized in that the bending section has a first collapsible guide line, a second collapsible guide line, and a third collapsible guide line, hence when the piston stops, the acting zone of the air stop sheet turns on relative to the plane of the top of the head at the open angle θ, or characterized in that the bending section has a first collapsible guide line and a second collapsible guide line, wherein the acting zone has a height different from a height of the positioning zone.