Crystallization process of Se85-xTe15Sbx (x = 2.7, 7.5, 10 and 15 at %) chalcogenide glasses has been studied by using differential scanning calorimetry (DSC) with different heating rates. These glasses are found to have a double glasses transition and overlapped crystalline phases for Se70Te15Sb15 glass while single glasses transition and single crystallization stage for other glasses. Glass transition temperature, Tg, onset crystallization temperature, Tc, and peak crystallization temperature, Tp, are found to be dependent on composition and heating rates. Values of various kinetic parameters such as activation energy of glass transition, Eg, activation energy of crystallization, Ec, Hurby number, Hr, thermal stability, Sp, rate constant, Kp, and Avrami exponent, n, are determined for the present systems. Results indicate that rate of crystallization is dependent on thermal stability and glass-forming ability. Crystallization mechanism occurs in two dimensions for studied compositions. Crystalline phases resulting from DSC and scanning electron microscopy have been identified by using X-ray diffraction.