Optical fibers doped with highly concentrated CdSe/ZnS quantum dot (QD) are prepared,and their photoluminescence (PL) spectra are measured. The doping concentration and the fiber length,corresponding to the maximum PL peak,are determined by analyzing the respective PL spectrum. Compared with low doping concentrations,the observed peak intensities enhance greatly within 1 cm fiber length,and decrease gradually as the fiber length increases. The exciting intensity at 473 nm shows an exponential attenuation with an extinction coefficient of 0.26-1.02 cm-1. Given the exciting intensity and the exciting wavelength,the total amount of QD that can be added to obtain the maximum PL emission is a constant. A red shift of the PL-peak wavelength reaches to 8-15 nm,depending on the doping concentration and the fiber length. These results provide a reference in the development of possible quantum dot-doped fiber amplifiers in the future.