In view of the problems of color distortion and unsatisfactory crack detection effect in aerial image of insulators in fog, an improved Hough transform method is adopted to locate and detect the cracks of insulators in fog. Aiming at the disadvantage of color distortion, the formula of perspective is improved by the absolute value of the difference between atmospheric light intensity and dark channel, so as to improve the color distortion of bright areas such as blue sky and white clouds after defogging. For the obstacle of insulator positioning and crack detection, the feature that the center of the ellipse is the point with the minimum maximum length to the edge of all points inside and outside the ellipse is proposed, and the center of the circle is calculated quickly to reduce the Hough parameter dimension and calculation amount, so as to realize insulator positioning in the image. Finally, the combination of peak detection and zeroing in Hough space is used to solve the problem of time-consuming and low accuracy of traditional Hough transform linear detection algorithm. By setting the threshold value, the generation of false cracks and over connections can be reduced, and the cracks can be detected quickly and accurately. The simulation results show that the improved Hough transform proposed in this paper improves the detection rate of insulator cracks in fog by 1.4 times and the accuracy rate by 5.5% compared with the traditional Hough transform.