In order to prolong the life of steel worm pair used in track tension adjuster, a test method was designed to evaluate the effect of hardness on the fretting wear behavior of steel worm gear on a SRVⅣoscillating friction and wear tester. Through this method the fretting wear behavior of 40CrNiMoA steel-18Cr2Ni4WA steel with different hardness matching was studied under dry sliding condition at room temperature. The results show that in the steel worm gear pair composed of 40CrNiMoA steel and 18Cr2Ni4WA steel, the fretting wear volume loss of 40CrNiMoA steel decreased and that of the 18Cr2Ni4WA steel worm material increased with the hardness of 40CrNiMoA steel increasing. When the hardness of 40CrNiMoA steel is about HRC49, fretting wear volumes of the worm specimen was equal to that of the worm wheel specimen. Based on the experimental results, reasonable hardness matching for prolonging the life of steel worm pair used in track tension adjuster was proposed.