The microscopic fluorescence spectra and imaging of excised lung tissue sections were studied under a novel microspectrophotometer system using a He Cd laser light at 442 nm. Differences of the intrinsic autofluorescence distributions in different tissue layers, i.e., epithelium, mucosa and cartilage, were observed in normal and malignant lung tissues. The results show that the study of microscopic fluorescence on various tissue layers can be used to explore the origin of spectral differences between normal and abnormal lung tissues, which is very useful for the better understanding of the mechanism of the early cancer diagnosis using the laser induced autofluorescence technique.