Abstract The crystallization rate, crystallinity, Avrami exponent and melting temperature of the blend system of PC with PETand EPDM were investigated by means of depolarized light and differential scanning calorimetry respectively. Both of the crystallization rate and crystallinity of the blends of PET with PC, and with or without EPDM showed a marked drop with the increase of the content of PC. In contrast, the crystallization rate of blends of PET with EPDM was increased to a maximum when the weight fraction of EPDM was about 5%, but the crystallinity showed little change when the amount of addition of EPDM was up to 10%. The Avrami exponent, calculated on the basis of Avrami equation, did not seems to be influenced by the composition of blends. The DSC thermograms of annealed samples showed double melting peaks. The melting peak at higher temperature, i. e. melting point, shifted to the side of higher temperature with increasing PC content slightly and the melting peak at lower temperature shifted to the side of higher temperature when the annealing temperature was raised or the annealing time was prolonged.