In this work thermal analysis of amorphous semiconductor In4Se96-xSx (x=0, 4, 8, 12) has been studied by Differential Scanning Calorimetry (DSC) under non-isothermal conditions at four different heating rates i.e. 5 degrees C/min, 10 degrees C/min, 15 degrees C/min, 20 degrees C/min. Two well defined crystallization exothermic and endotherm peaks are exhibited in the DSC thermogram. Glass transition temperature (T-g), crystallization temperature (T-c), activation energy for structural relaxation (E-t), activation energy of crystallization (triangle E-C), crystallization enthalpy (triangle H-C) and order parameter (n), are estimated by using different methods of analysis such as Johnson-Mehl- Arvami (JMA) model, Ozawa and Kissinger under non-isothermal condition. Surface morphological analysis of annealed thin film at 90 degrees C have been carried out by Scanning Electron Microscope (SEM) which reflects development of grains. Energy Dispersive Analysis by X-ray (EDX) analysis shows the perfect compositional elements in alloy. On the basis of observed experimental data, it's found that T-c-T-g is maximum and crystallization enthalpy (triangle H-C) is minimum for In4Se88S8 .This indicates that glass In4Se88S8 is thermally most stable.