Abstract: This paper reports a new method for determining nifedipine based onthe unstable character of nifedipine to light. The absorbance was measured at 350 nm be-fore and after light irradiation. In this method, the contents of nifedipine in tablets weredetermined by differential absorbance (ΔA)and the assay of nifedipine was not affected byother components. Calibration graph was linear in the range of 10 ～60/μg/ml for ΔA.The precision of the method was: 1.3% within- day and 1.9% between- days. The average recovery for nifedipine was 99.69%. The method is not only better in specificity andrepeatability but also simple and rapid, it would be a new way of assay for nifedipine.