Recently, it has been reported that suitable garment pressure contributes to accelerating human blood circulation, improving sports performance and alleviating sports fatigue. In this study, effect of pressure exerted by knee-high gradient compression socks (GCS) on the lower limb muscles was investigated. Two healthy male college students volunteered to participate in this study. They were asked to run on a treadmill at a speed of 10 km/h with a GCS worn on one leg and a usual sports sock worn on the other leg until being tired out. During running, the surface electromyography (sEMG) of two lower limb muscles —— gastrocnemius medialis of the right leg (R-GM) and the left leg (L-GM) was recorded simultaneously. It was found that: pressure exerted on the lower limb by GCS gradually decreased from ankle to below-knee; GCS pressure helped to reduce muscle oscillation; wearing GCS seemed to help to reduce muscle fatigue during running.