The absorption coefficient, absorption and emission cross-sections of CdSxSe1-x/ZnS (core/shell) Quantum Dots (QDs) were determined by measuring absorption-emission spectra of the QDs with different composition ratio x. The absorption cross-section of QDs shows an increase with the increase of QD size, and shows a decrease with the x increase. In addition, CdS0.4Se0.6/ZnS QDs doped fibers are prepared in a solid fiber core of ultraviolet gel in the doping concentration of 0.1~5 mg/mL. The absorption decay rate of 473 nm laser pumped into the QDs doped fiber are measured for different doping concentrations. There is evidence to show that the absorption-decay rate and the cross-section are weakly associated with the doping concentration, and the photoluminescence-peak intensity of the doped fiber varies with the fiber length and the doping concentration. There is a saturating doping concentration and desired fiber length corresponding to the maximum photoluminescent intensity. The experimental results provide a support for development of CdSxSe1-x/ZnS-QDs doped photoelectronic devices in the future.