Traditional methods of wheel-rail contact forces measurement all need strain gauges on wheel sets or rails. The shortcomings of strain gauges such as zero-drift, poor anti-interference property and instability of test system can’t meat wheel/rail force test requirements in high-speed railways. A method based on PVDF piezoelectric sensing technology is presented for the test of wheel/rail contact force. Firstly, on the basis of the theory of vehicle-track coupling dynamics and by means of simulation software ADAMS/Rail, a three-dimensional train-track simulation model is established. Secondly, the modes and characteristics of wheel/rail impact vibrations due to non-roundness of railway wheels are investigated in high-speed railway operation. The relationship between the range for acceptable roundness values and vehicle speed is determined. Finally, the view that it is of important significance to establish wheel/rail force real-time monitoring system is expanded, so that abnormal conditions caused by out-of-round wheels can be detected in time, to ensure high-speed railway traffic safety. The study is very important for enhancing the stability and economy signification of rail transmission.