A modified two-stage kinetic model is proposed to describe the crystallization/solidification from the melt state of a miscible binary blend system comprising amorphous poly(ether imide) (PEI) and crystallizable poly(butylene terephthalate) (PBT). Differential scanning calorimetry (DSC) was employed to monitor the isothermal melt-crystallization of the PBT/PEI blends. A nonlinear regression method was adopted for estimating the kinetic parameters in accordance with the modified two-stage series-parallel model in comparison with the Avrami model. The results suggested that the crystallization of the PEI/PBT blends could be more precisely described by using the modified model, which properly takes into account the changing mechanisms from early to later stage of crystallization. For practical applications, an optimal temperature window for solidifying PEI/PBT miscible blends may be determined by utilizing this model.