This paper studies deformation of CFRP at microscopic area and observing technique. Tensile test is carried out for CFRP specimen and digital image correlation (DIC) method is used to observe deformation of microscopic area, especially around its fiber interface. CFRP specimen is loaded by tensile testing machine for investigating deformation around vertical section of fiber. Diameter of carbon fiber used which is mainly interested in the specimen is micro scale, therefore scanning electron microscope (SEM) is used to gain high magnification and resolution pictures as they deforms. To achieve this in situ experiment, testing machine which can be used in SEM is developed. The essential to achieve DIC is selection of random pattern used to follow up change of the area, which greatly influences accuracy of result. Colloidal silica and the other particles are utilized for random pattern with adjustment of concentration. The pattern must be seen clearly and small enough compared to fiber vertical section. Through this research, examination of deformation observation at microscopic area and consideration of starting and fracturing procedure of CFRP are performed.