Randomized Hough transform (RHT) is an effective method for circle detection. But when dealing with multi-circle complex images,the random sampling will bring lots of invalid accumulations and result in a large number of calculations. In this paper,by selecting three points of the candidate circle,a fast detection algorithm of multi-circle with randomized Hough transform is presented. Experimental results demonstrate that the proposed scheme can quickly detect multiple circles,and has a strong robustness.