The invention discloses a piston rod for a grain dryer pressure cylinder. The piston rod comprises a piston rod body and a piston and further comprises a dustproof sleeve, a connecting sleeve, a gasket and a guiding sleeve. The dustproof sleeve is connected to the side, away from the piston, in the length direction of the piston rod. The guiding sleeve is connected to the piston rod, and the connecting position is closer to the piston than the connecting position of the dustproof sleeve. The connecting sleeve is located between the dustproof sleeve and the guiding sleeve, thermal-resistant sealing rubber is arranged on the side, away from the connecting sleeve, of the dustproof sleeve, the other side of the dustproof sleeve is located outside the radial direction of the connecting sleeve in an extending mode to be matched with the side face of the connecting sleeve, and the gasket is located between the connecting sleeve and the side of the dustproof sleeve. A first sealing ring is arranged on the side face of the connecting sleeve, and the guiding sleeve and the dustproof sleeve are in clearance fit. A plurality of second sealing rings are arranged on the radial inner side, matched with the piston rod, of the guiding sleeve, and a third sealing ring is arranged on the radial outer side of the guiding sleeve. A protrusion is arranged on the radial outer side of the piston, andthe surfaces, on the two sides of the protrusion, of the piston are sunken and provided with anti-abrasion sealing rings.