The influence of crystallization temperature on formation of the alpha- and beta-form crystals of syndiotactic polystyrene (sPS) was investigated by X-ray diffraction and non-isothermal differential scanning calorimetry analysis. For sPS samples without any thermal history, the crystallization temperature must be the intrinsic factor controlling the formation the a and P-form crystals. Being crystallized at different cooling rate from the melt, sPS forms the P-form crystal until the temperature cooled down to about 230 degreesC, and a-form crystal can only be obtained when the temperature was below about 230 degreesC.