This paper presents the dynamic analysis of curving behavior of railway vehicles. Curving simulation of vehicles running at low speed is important from a point of view of safety. But it haven't often been done and results of simulation usually different from measured them. Though the influence of leveling valves and differential pressure valves can be generally ignored in the case of simulation of vehicles running at high speed, the effects of them must be considered at low speed. Therefore we irproved A'GEM which is multibody dynamics software to add non linear air suspension with leveling valves and differential pressure valves. The results of curving of simulation were compared with experiments with good agreement.