Effects of cooling rate and crystallization and melt temperatures on the melting curves of predomi-nately β-phase isotactic polypropylene (IPP) were investigated by using DSC instrument. Experimental re-sults indicate that the magnitude of βmelting endctherm increases with decreasing cooling rate and withincreasing crystallization temperature. The temperature of melt has no effect on the β-phase crystallizationof IPP below 300℃, but a further increase of the melt temperature will destroy the β-phase nuclei,then the β-phase crystals will not be produced upon cooling. The linear growth rates of α- and β-phasespherulites were determined as a function of temperature between 123 and 140℃. It was found that thegrowth rate of βspherulites is higher than that of αspherulites below 140℃. Studies of the kinetics ofβ-phase crystallization of IPP were also made using a DSC instrument. The results obtained do not fitthe usual Avrami equation. But it can be described by kinetic theory of imcomplete spher Effects of cooling rate and crystallization and melt temperatures on the melting curves of predomi-nately β-phase isotactic polypropylene (IPP) were investigated by using DSC instrument. Experimental re-sults indicate that the magnitude of βmelting endctherm increases with decreasing cooling rate and withincreasing The temperature of melt has no effect on the β-phase crystallization of IPP below 300 ° C, but a further increase of the melt temperature will destroy the β-phase nuclei, then the β-phase crystals will not be produced upon cooling. The linear growth rates of α- and β-phasespherulites were determined as a function of temperature between 123 and 140 ° C. It was found that the rate of βspherulites is higher than that of αspherulites below 140 ° C. Studies of the kinetics of β-phase crystallization of IPP were also made using a DSC instrument. The results obtained do not fit the usual Avrami equation. But it can be described by kinetic theor y of imcomplete spher