In the present paper the fluorescence spectra of the blood serum excited with different wavelength were measured with the fluorescence photometer RF5301 (SHIMADZU) made in Japan. The relationship between the fluorescence spectra of the serum and the wavelength of the excitation light was studied during the experiment. The experimental results show that the linetype and peak wavelength of the fluorescence spectra of serum excited by ultraviolet radiation with different wavelength are almost the same, and they do not depend on the excitation wavelength. But the fluorescence peak value changes with the excitation wavelength. There are two high intensity emission intervals in the fluorescence spectra. One of these is from about 300 nm to 410 nm, and the other is below 310 nmr The fluorescence spectra are mostly centralized in the first interval, and the wavelengths of fluorescence peaks were found around two locations: one is near 330 nm and the other is near 370 nm. At this time the strife phenomena occur. When the excitation wavelength is about 250 nm or higher, the fluorescence peak only occurs at 330 nm, and the optimal excitation wavelength is 300 nm. While the wavelength is greater than 320 nm, the fluorescence intensity of the first interval begins to fall, while that of the other augments. And at this time the peak of wavelength of fluorescence is 452 nm. This study provides the experimental foundations for advanced study and applications of the characteristics of fluorescence spectrum of blood serum, and also offers the references to the wavelength selection of excitation light in the application of the photo-induced fluorescence spectra diagnostic technology.