Abstract: Narrow gap arc welding on rail is a new way of rail welding to adapt to local condition, and its post weld heat treatments are researching by some researchers. This paper uses the therma simulator of Gleeble-1500D to simulate a series of normalizing treatments on welded joint with narrow gap arc welding, and then measures the Rockwell hardness, watches the microstructure and combines the Vickers microhardness to analyse the welded joint. The result shows that the maximum temperature of normalizing between 925℃ to 935℃ maybe the best choice, which can make the hardness of welded joint be uniformity distributing, and the effect of grain refining be obvious, and softened zone be eliminated. So it can offer some advice for normalizing treatments in the production practice.