This study was designed to monitor localized muscular fatigue with the power spectrum medium frequency of surface myoelectric signal, and test the muscular fatigue of body bices. While sustaining constant force, isometric muscular contraction, the initial past decreasing rate of medium frequency curve, the absolute value of the fitting straight line slope, was increased with the degree of the muscular fatigue. With this rate, it was possible to quantitatively judge the state of the muscular fatigue, reduce the physical consumption and muscular uncomfort of recipients.Monitored parameters were acquized from surface myoelectric signal, reallzing the nonvasive in the monitoring process.