Improved pen structure

The utility model relates to an improved pen structure, which is combined with an upper and a lower pen cylinders to store a cartridge in, causing the cartridge to be downwards penetrated through the lower pen cylinder to carry out the movement of writing words. The top surface at the inside of the pen cylinder is provided with a concave chamber for positioning an elastic element which is downwards butted with the top end surface of the cartridge, and the outside of the lower cylinder is sheathed with a sleeve cylinder, causing a convex post of the sleeve cylinder to pass through and be convexly extended in a through hole of the lower pen cylinder. When the pen is dropped to the ground by inadvertence, when the cartridge is dropped vertically to crash the ground, the cartridge is capsulized in buffer into the lower pen cylinder because of the elastic force action of the elastic element, and then, the cartridge is reset in the original position, so the breakage and spoilage of the cartridge is avoided, and the service life is effectively extended. When the writing force is excessively big, the bottom end part of the holding sleeve cylinder can be pressed, causing the convex post to be convexly extended inwards to be butted on the outside of the cartridge for preventing the cartridge from capsulizing at writing time, so the utility model is suitable for different users who write in different writing force.