A compact portable laser-induced fluorescence detector, which includes an excitation source of 405nm stable spectra diode laser, a fluorescence collection module based on a fluorescence optical fiber probe and fibre, a fluorescence analysis module of a grating spectrometer. The study on the photodynamic diagnosis of squamous cell skin carcinoma of SKH-1 hairless mouse using the 405nm laser-induced fluorescence spectra of PpIX induced by ALA was done.