Plating of fractures results in osteoporosis beneath the plate because of the stress-shielding effect,so we designed a new plate system with a washer inserted between screw hole and screw. This study was performed to analysis the reaction of bone-plate system to cyclic vertical compressive loading.The in vitro experiment demonstrated that the new plate fixed to a osteotimized stimulant bone loosened due to fatigue damage of washer materials and thus decreased its stress-shielding rate with cyclically loaded l0 times. While the new plate-undrplate construct didn’t fail early with cyclically loaded 10 times before early fracture union culd occur. The investigation showed that the new plate system provided strong initial fixation and gradually loosened with cyclic loading in vitro and therefore should decrease the stress-shielding effect when applied in vivo.