Abstract: The forming precision of railway wheel is affected seriously by the phenomenon of web thinning during its rolling process. The wheel web thinning was analyzed based on simulation by using finite element software SuperForm. The metal volume flow due to the web extension during wheel rolling was calculated based on the theoretical of metal flow. The result shows that the fundamental cause of the web thinning during wheel rolling is that metal volume of flow from the rim to the web cannot supplement the required volume increase caused by the web length extension; The web thinning mainly takes place in the 1/4 round from the edging roll deformation region to the main roll deformation region of every rounds in the mid- term rolling process; The web thinning amount increases with increasing of the rim expansion rate and the inner diameter of the rim, and increases with the decreasing of radial reduction to the rim at the web roll side.