ulfonated syndiotactic polystyrene ionomers (SsPS) with 1.8 mol% degree of sulfonation have been studied.SWAXD shows that the crystallinity of SsPS ionomers was decreased with increasing diameter size of the counter ions and sPS ＞ SsPS-H ＞ SsPS-K ＞ SsPS-Zn. Moreover, SsPS ionomers only have α crystal form, while original sPS has two crystal forms: α and β crystal form. TGA shows that the thermal stability of SsPS ionomers is higher than that of the original sPS and SsPS-Zn ＞ SsPS-K ＞ SsPS-H. DSC shows that all the glass transition temperatures (Tg) of SsPS ionomers are higher than that of the neat sPS and SsPS-Zn ＞ SsPS-Na ＞ SsPS-K ＞ SsPS-H. However, the melting temperature (Tm) and crystallization peak temperature (Tp) of SsPS ionomers are lower and SsPS-H ＞ SsPS-Zn ＞ SsPS-K ＞ SsPS-Na, while the crystallinity (Xc) of SsPS-Zn is the lowest. Nonisothermal crystallization kinetics shows that the Avrami index of sPS and SsPS-H are both about 4, suggesting the nucleation growth of SsPS-H with lower degree of sulfonation still keeps its threedimension form. FTIR spectra of SsPS ionomers show a splitting absorption band for asymmetric stretching vibration of sulfonation group. The CH in-plane bending vibration of benzene ring shifted to higher wavenumber and the symmetric stretching vibration of sulfonation group changed slightly with different counter ion neutralized SsPS ionomers.