Abstract: The near-IR absorption spectra of PbSe nanocrystal(quantum dot)with 5.5nm diameter are measured.The peak of absorption cross section of the PbSe quantum dot is determined by the quantum-dot concentration，diameter and Beer-Lambert law.The doped technics making the quantum-dot fiber in a laboratory are presented by a vacuum method，an injection method and an infiltration method available.Silicic acid sol used as a dopant in the fiber core is obtained.Such silicic acid sol possesses a refractive index near the general fiber claddings.

Key words: quantum dot, quantum dot fiber, absorption cross-section