Laser-induced fluorescence spectroscopy is a widely-used medicinal spectral technique that has been used on the diagnosis of tissues and cells. In this paper, we measured the auto-fluorescence of serum of lung cancer patients and healthy people using the technique of laser-induced fluorescence spectroscopy. Principal component analysis and discriminant analysis were used to analyze the data of fluorescence spectra, and an accuracy rate of 84% was obtained. Our preliminary research proved the possibility of using auto-fluorescence of serum for the diagnosis of lung cancer.