The oleic acid-capped PbS nanocrystals were synthesized by hot-inject ion method.With ligand replacement,partial oleic acid ligand is exchanged and r eturns to ethanolamine-capped PbS nanocrystals.The J-V behaviors of PbS/Al Schottky junction by different ligand-capped PbS quantum dots are discussed by thermionic emission theory comparatively.The results suggest that the uniform ity of PbS thin film surface can improved with short-chain ligand and then be tter Schottky contact performance is achieved.The ideal factor n is 3.8, significantly lower than that of PbS quantum dot with oleic acid ligand (n=4.6).Meanwhile,the increased barrier height and improved reverse leakage current are presumably attributed to the sho rt ligand replacement.