The renormalization of effective masses of polaron spin states in chiral structures is studied based on the direct spin-phonon coupling, in which the simple formulas for the renormalization of effective masses are derived for polarons with spin-up and spin-down states using a linear-combination operator method. The theoretical calculations show that the effective masses are renormalized significantly with increasing the cut-off wave vector of phonon modes and the renormalized magnitudes are different for right-handed and left-handed structures. Moreover, the renormalized magnitude for the spin-down state is larger than the spin-up one. This asymmetrical behavior naturally gives rise to very different conductivities for spin-up and spin-down states as electrons transmitted through the systems. These results not only enrich the microscopic origin of CISS mechanism, but also enlighten more experimental ways to explore CISS.