In light of the problem that a midpoint chord model cannot restore the real value of rail irregularity, an analysis was conducted on rail corrugation and the corresponding midpoint chord′s measured data, both of which were proven to be periodic. On this basis, a new approach was proposed that measures multi-chord and thereby estimates the rail corrugation value. Using different chords to measure the same rail helps avoid the special wavelength amplitude gain from being zero. The frequency and location of rail corrugation can also be acquired from the multiresolution of wavelet transforms. Results showed that this method can select rail corrugation from midpoint chord measurements and restore its original value through calculation. Therefore, it is suitable for the rapid test and estimation of rail corrugation amplitude in engineering.