To solve the problem of the typical histogram equalization method used to enhance cardiac coronary artery angiography images, a novel method based on histogram equalization is proposed. Firstly, the Fuzzy C-Means clustering algorithm is adopted to realize the histogram's partition, and the control threshold is selected. Then histograms of sub-level are redefined by adopting local histogram modification to construct gray transfer function. Finally the enhancement result of sub-level is composed. The experimental results demonstrate that this image enhancement algorithm could significantly enhance detailed regions and produce little noise over-enhancement.