Abstract: In order to detect whether the collision occurs between particle and bubble in flotation accurately, a collision detection method of particle and bubble, which based on morphological image processing and Otsu method, is presented. First of all, It utilizes image pre-processing to optimize images, the target area and the background area are segmented by Otsu method. Then, particles and bubbles are fitted to a circle combined with the least-square method, it’s convenient to obtain the coordinate information and radius. Finally, the position of all particles is extracted to an image, which achieves the particle tracking and avoids the complexity of the continuous frame image tracking. The results indicate that this algorithm can detect the collision between particle and bubble quickly, and the working hours of manual test are saved effectively.