The FLS900 Steady-state fluorescence spectrometer is used to test the normal and alcohol blood in vitro when radiated by continuous laser,and the variation components in blood and the fluorescence characteristics decayed with the time are obtained.The results show that the location of the fluorescence peak can not change when excited by 407 nm laser,only the intensity of the emission peak in the 605 nm decreases slowly.But the fluorescence spectrums have a wave mutation in 14 hours and 10 hours respectively,and have a strong fluorescence peak in the 474 nm eventually.Through the analysis,it can be concluded that the laser can put off the decay time of blood in vitro obviously and also can partly repaired the erythrocyte destroyed by the alcohol,but continuous irradiation by laser led to the change of cells morphology and then accelerated the hemolytic process,thus produced a lot of fluorescence material-reduction of nicotinamide adenine dinucleotide.The result will supply a valuable reference to the research on activity of the blood cell and the functional structure of the blood.