The characteristic analysis of cement clinker using light microscope can evaluate not only the quality of cement but also making process. Thus this study analyzed clinkers having different burning conditions by reflective light microscope. As heating and cooling rates is decreased, alite and belite minerals grew and especially cooling rate had an effect on the growth of belite. Futhermore as the retention time in max. temperature got longer by twenty minutes, alite and belite minerals grew more about 5 $mu extrm{m}$. In the case of temperature 1400$^{circ}C$ in max, the size of belite was suitable but alite was not suitable with the size of 10～15 $mu extrm{m}$.