To get the match of front wheel caster angle versus steady cornering velocity, exploring for the real ways of improving stability of high-speed cornering, based on the equations of 2 free-degrees vehicle dynamic and steering system, a calculating formula was founded by using the Routh-Hurwitz criterion. A vehicle made in China was used as samples, and according to the formula its caster angle was calculated versus steady cornering velocity. The tests of front tire footprint and steering wheel angle step input were carried out in term of state criterion GB/63232—1994. The tests proved that the formula is characterized by a precision in predicting the match of front wheel caster angle versus steady cornering velocity.