Targeted muscle reinnervation (TMR) technique has been successful in many amputees for providing sufficient electromyography (EMG) signal to control advanced prosthetics. However, it seems to lack further understanding of the recovery progress of muscle functions after targeted muscle reinneveration surgery. In this study, a rat TMR model was developed to investigate intramuscular EMG activity changes after reinnervation. Using the discrete wavelet decomposition and average rectified algorithm, the recorded EMG showed a gradual improvement in the reinnervated muscle within four weeks. Future work will be performed to further assess the efficiency of reinnveration therapy after the surgery.