The thinbarbituric acid(TBA)fluorescence spectrophotometry of lipoperoxides(LPO),at present used for research,has been improved. This assay of serum LPO involves a hydrolysis in a diluted glacial acetic acid solution at 100℃ for 60 min and the hydrolysis product malondialdehyde (MDA) forms complex with TBA the methanol precipitation of serumproteins reduces nonspecific interference.The fluorecence intensity of the MDA-TBA complex is measured at excitation wavelength 515nm and emmission wavelength 550nm. The method is simple,rapid, accurate and steady. The fluorescence intensity is positively correlative to the LPO concentration in the range of 0～20μmol/L. The minimum detection limit is 0.16μmol/L.The average recovery rate is 105.08%. Precision(CV) is 4.23%.