Crystallization and melting behaviors of syndiotactic polypropylene(s-PP) were studied by using differential scanning calorimetry(DSC). s-PP exhibits the double melting behavior which strongly depends on a thermal history of smaples. To understand the morphology of two crystals formed during isothermal crystallization, DSC experiments were carried out for samples prepared with different cooling rates. During the crystallization process, s-PP forms a kinetically favored structure with higher melting temperature and a thermodynamically favored structure with lower melting temperature. The relative amounts of these two structures are dependent on the cooling rate of crystallization and annealing conditions.