Abstract: Via measuring results of phase compatibility and interference effects between polystyrene (PS) and polyvinyl benzyl chloride (PVBCl), the influence on the phase separation status of the two substances in the cured film and shell from solution mixed with PS and PVBCl was studied using the infrared microscopic chemical image, and the phase separation of the two polymers of the microspheres obtained under different processing conditions was studied by the infrared microscopic chemical image. The results indicated that the established method can be used to analyze the phase separation of PS and PVBCl in the shell of microspheres by qualitative or semi-quantitative, and the large testing uncertainty caused by the interference effects in polymer microspheres, can be optimized at 40 ℃ because of the better phase separation of these two polymer substances. This study provides a method to investigate the conditions of preparation of heterogeneous dual hemispherical polymer, and to characterize the phase separation of polymer by infrared microscopic chemical image. However, this method affected by the spatial resolution is not suitable for the sample with size less than 6.25 m6.25 m.