Abstract: The residual stress distributions of rail joint welded by narrow-gap arc welding are measured before and after heat treatment and are compared, and then the influence of welding residual stress on the drop-weight test performance of rail welded joint is analyzed by combining the drop-weight test results with fracture appearance. The experimental results show that, there exists a comparative large residual tensile stress in the parts of web and jaw of rail welded joint before heat treatment, where the crack source forms easily under the action of shock load from drop weight, afterwards, the crack extends and propagates to base metal along the rail web, until the rail welded joint ruptures. The maximum value of residual stress in rail welded joint declines 1/2~2/3 after heat treatment, the resistant capability of rail welded joint to shock load is improved significantly, and the rail welded joint ruptures vertically along the weld center or heat affected zone during drop weight test. When there is larger residual stress within rail welded joint, the crack is easy to generate and accelerating propagate in the part existing larger residual stress under the action of shock load from drop weight, and resulting in final fracture.