Abstract： For the problem of damping matching of subway secondary verticalsuspension system, an analytical calculation method of optimal damping ratio was provided. Based on the analysis of the typical track spectra, the track verticalprofile irregularity model built by the curve fitting method was established to effectively reflect the actual track traffic conditions and meet the theoretical analysis of vehicle running stability. According to the 1/4 vehicle threedegreeoffreedom verticalvibration model, the analytical calculation model of subway secondary verticalsuspension optimal damping ratio was built by the theory of random vibration and residue theorem. The model was aimed at minimum of mean square value of the vibration acceleration and was validated by the example calculation and simulation results. The maximum relative deviation of damping ratio between the analytical calculation value and the simulation value is only 2.55%. It shows that the analytical calculation model of subway secondary verticalsuspension optimal damping ratio is correct.