An alternative implementation of confocal scanning microscopy has been developed to construct a compact and anti-jamming confocal microscope by using fiber optical components. A fiber optical confocal scanning microscope (FOCSM) in reflected mode was bulit for this purpose. The influence of fiber-collective lens parameter A and numerical aperture of objective lens on the system imaging resolution is analyzed. Consequently, an optimum collective lens was chosen to improve the system resolution with certain fiber and objective lens. In system testing, submicron transverse resolution and micron axial section resolution with good imaging stability has been obtained. The instrument will be used for three-dimensional imaging of the microstructure in the fields of material sciences, biology and medicine.