根据Ｎ－乙酰－Ｌ－半胱氨酸与氯化钯（ＰｄＣｌ２）反应，生成一种稳定的黄色化合物，我们建立了比色测定复合结晶氨基酸注射液中的ＮＡＣ的方法。测定波长为３７５ｎｍ，检测结果重现性好，变异系数是３．９％，回收率范围在９３．１％～１００．２％之间，检测下限为０．１６３μｇ／ｍｌ。该方法比经典的电量滴定法灵敏度高、精确性好，较高压液相色谱法操作简便、费用低。 According to the reaction of N-acetyl-L-cysteine ​​and palladium chloride (PdCl2), a stable yellow compound was formed. We established a method for the colorimetric determination of NAC in compound crystalline amino acid injection. The detection wavelength was 375nm, the detection result was good, the coefficient of variation was 3.9%, the recovery range was between 93.1% and 100.2%, and the detection limit was 0.163μg / ml. This method is more sensitive and accurate than the classical coulometric titration. Compared with high-pressure liquid chromatography, the method is simple and easy to operate with low cost.