The spectral analysis technology applied to some blood diseases diagnosis is convenient and speedy. The experimental result shows that the line type and peak value of the fluorescence spectra of serum excited by ultraviolet radiation with different wavelength remain the same, but the fluorescence peak value changes with the wavelength of the blazed light. The present paper studied how the serum fluorescence spectrum changes with the serum concentration, adopting Shimadzu Corporation (Japan) fluorescence photometer RF5301, and provided the experiment basis for disease diagnosis by hemanalysis. The experimental result shows that the fluorescence spectrum of serum is different under the excitation of different monochromatic light, the relative fluorescence intensity of serum increases with the serum concentration when excitated with 220, 230 and 310-420 nm monochromatic light, but the serum fluorescence intensity decreases while the serum concentration increases when the excitation monochromatic light is between 240 nm and 420 nm. The experimental research found that the serum concentration quenching and absorption effect is not obvious when the experimental sample is excitated by 220, 230 and 310 to 420 nm monochromatic light, and the fluorescence stimulation plays the main role. The serum concentration quenching and absorbing effect is obvious, so the fluorescence intensity becomes weaker and weaker with serum concentration increasing when the sample is excitated by 240 nm to 300 nm monochromatic light. This work provides the experimental basis for the choice of serum concentration in the study of serum fluorescence spectrum.