Wearing a myoelectric prosthesis is the most effective way to restore the lost limb functions for amputees in their daily life. Unfortunately, the control performance of myoelectric prostheses is commonly affected by a number of factors that limit their practical use. When most of the factors have been investigated in the previous studies, it remains unclear how muscle fatigue negatively affects the prosthetic control stability. In this pilot work, our goal was to study the muscle fatigue that was induced by wearing a prosthesis with different weights. The effect of the weight of the prosthesis on muscle fatigue was estimated by surface electromyography (sEMG) signals that were recorded from residual limb muscles of a transradial amputee before and after wearing the prostheses. Three features, mean absolute value (MAV), mean frequency (MNF) and median frequency (MDF), were extracted from the EMG recordings and then the maximum voluntary contraction (MVC) was represented by the MAV and the muscle fatigue tendency was estimated from the MDF and MNF. The preliminary results of the study indicated that the greater the weight of the prostheses, the more likely it was to cause muscle fatigue. Importantly, our results showed that the muscles of intact limb recover much quicker than the disabled side from muscle fatigue. This study could provide the guidance for amputees to select a proper prosthesis base on individual load capacity, and decide appropriate usage time in daily training activities.