This paper presents a general approach for dealing with the thermal vibration characteristics of functionally graded porous stepped cylindrical shell (FGP-SCS) by employing characteristic orthogonal polynomials. The thermal vibration characteristics including free vibration, steady-state and transient response are investigated in detail. The governing equations are derived by Rayleigh-Ritz method and the displacement admissible functions are denoted by using characteristic orthogonal polynomials. The FGP-SCS is divided into N segments with different thickness and the coupling of adjacent segment is realized by connecting springs. The boundary conditions of FGP-SCS can be determined easily by selecting the proper stiffness values of boundary springs and the boundary conditions including classical and elastic boundary conditions. Three temperature distributions including uniform, linear and nonlinear distributions and two porosity distributions including even and uneven porosity distributions are taken into account. Meantime, the influences of some key parameters including power law index, porosity volume fraction, temperature change, geometric structure on the thermal vibration behaviors of FGP-SCS are investigated in detail.