Image corner detection is one of fundamental problems of computer vision and image processing research. Most of the corner detectors detect too much redundant information and increase unnecessary computational costs. We present a new mask that uses only the margin pixels of two circles. To avoid the unnecessary computing, when the mask is scanning areas of similar intensity, the mask will go on with the next nucleus directly. Then a fast corner detection algorithm based on a double circle mask is proposed. We test the performance of our algorithm on digital signal processing and the experimental results show that our new detector performs better and costs less time than the three other methods to which it is compared.