A new synchronous fluorescence spectrophotometry method was developed for the determination of trace cephradine in animal food. The method was based on the condition that Cephradine was degradated in acidic condition and fluorescence intensity of its degradation product was increased by Twain-20.The degrada-tion condition and wavelength difference(△λ) were selected. The effects of heating time, the volume of sulfuric acid, pH, the effect of type and amount of surface active agent on the fluorescence intensity of degradation product were discussed. The results showed:1.5 mL 2.0 mol/L sulfuric acid was selected, heating time was 120 min, the buffer of Na2CO3-NaHCO3 was used to increasing pH to 10.6,1 mL 5%Twain-20 solution was added. The standard and sample solution were putted into 1cm fluorescence cuvette, Synchronous fluorescence spectrums were scaned from 420 nm to 550 nm,△λwas 90,the fluorescence intensities were readed at 468 nm. The protein in food sample were precipitaded by acetonitrile. In the range of 0.02μg/mL-2.00μg/mL, the con-centration of cephradine and the fluorescence intensity of its degradation product had good linearity, the corre-lation coefficients was 0.999 2,the detection limit was 2.71 ng/mL. At spiked levels of 0.40μg/mL to 0.60μg/mL, the recoveries were 93.91%to 96.90%,the relative standard deviation was 0.50%to 0.90%(n=3).The new method could be used for residue cephradine in animal food.%基于头孢拉定酸性降解产物荧光强度更强，吐温-20能提高降解产物荧光强度，建立测定动物性食品中头孢拉定残留量的同步荧光分光光度法。对降解介质及波长差进行了选择，讨论加热时长、硫酸体积、pH值、表面活性剂种类及用量对降解产物荧光强度的影响。结果：选择1.5 mL 2.0 mol/L硫酸溶液，加热120 min，用Na2CO3-NaHCO3缓冲液调pH值到10.6，加入1 mL 5%吐温-20溶液，在1 cm荧光比色皿中，于发射波长λem420 nm～550 nm内，△λ为90 nm条件下扫描测定，468 nm处读出荧光强度。应用加入乙腈沉淀蛋白的方法对动物性食品进行前处理。在0.02μg/mL~2.00μg/mL范围内，头孢拉定浓度与降解产物荧光强度呈良好线性关系，相关系数为0.9992，检出限为2.17 ng/mL。加标水平在0.4μg/mL～0.6μg/mL范围内，回收率为93.91%～96.90%，RSD为0.50%～0.90%（n=3）。建立的新方法可用于动物性食品中头孢拉定残留量检测。
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