Rail wear, rolling contact fatigue and other diseases will reduce the rail life, increase maintenance costs and even threaten vehicle safety. In order to explore the impact of rail profile optimization on vehicle dynamic performance, 3 kinds of vehicle dynamics models for locomotive, passenger car and freight car were established, and optimized a section of the domestic small radius curve rail profile, compared the wheel-rail relationship by minimum distance search method and calculated the dynamic curve passing performance of the vehicle by dynamic simulation software Simpack. The results showed that: the contact range on high rail of the curve was reduced from 47 mm to 28 mm after rail profile optimization, the contact probability at track distance was significantly lower than before, and rail side grinding was obviously decreased; the wheel-rail contact points on the low rail were concentrated on the top of track after optimization which could avoid full light strip phenomenon; rail profile optimization could decrease the wheel rail lateral force by 3.3%-21.1%, and decrease lateral wheelset force by 6.9%-21.9%, but the effect of wheel rail vertical force was not obvious; rail profile optimization could reduce the rate of wheel load reduction, derailment coefficient and wear power, improve vehicle running safety.