In order to explore the influence law of train wheel old flat spot on wheelrail impact, a rigidflexible coupling model of highspeed train considering flexible wheelsets and the finite element contact model of flat spot injury were established. The influence of single or double flat spot on wheelrail impact in different position distribution was analyzed to avoid the rail jump impact under the running state, in order to guarante the operation safety and provide basis for determining the limit of wheel damage during the safe operation of highspeed EMU. The analysis results show that the wheelrail vertical impact force generated by the old single flat spot first increases then decreases with the increase of the vehicle speed, and reaches the peak value at 100 km/h; if the speed is between 100~200 km/h, when the interval between the double flat spot is below 70°, the first old flat spot has a gain effect on the second old flat spot,when the interval is above 70°, the gain decreases significantly and both flat spot can be regarded as the independent flat spot; when there is a double flat spot with a length of 30 mm on the wheel, the maximum impact stress can reach 1 059 MPa after rail jump.