Objective To establish a experimental method for evaluating nerve regeneration after operation by means of tracing the retrograde axonal plasm flow by 125 I HRP Methods Eighteen SD rats were used The right sciatic nerve of mouse was transected at the site 0 8cm distal to sciatic notch and then anastomosed immediately Four weeks later,500?l of 125 I HRP solution was injected into the right musculi triceps surae The right sciatic nerve segment proximal to the anastomosis site was cut for checking up the intensity of radioactivity in each tissue at 24 hours after injection The fiber number of nerve distal to the site of anastomosis were calculated The relationship between the intensity of radioactivity and the fiber number was analysed Results The relationship between the intensity of radioactivity of sciatic nerve segment proximal to the site of anastomosis and the fiber number of distal sciatic nerve segment was correlation and there was statistic significance. Conclusion The status of nerve regeneration distal to the site of anastomosis can be evaluated by means of intensity of 125 Iodine in the nerve segment proximal to the site of anastomosis