Feeding is one of the primary factors determining efficiency and cost in aquaculture. In order to improve breeding efficiency, a new method of measuring fish feeding intensity based on depth image was proposed in this paper.This method is not limited by lighting conditions of aquaculture farms, and it does not rely on clear water or stable background. Through processing the depth data, the fish target foreground extraction and background image removal are realized with least amount of calculation, and clear fish feeding images are obtained by the depth image technology.The total number of the target pixels in the depth map is used to estimate the number of the feeding fish. Combined with the change rate of the target pixels, the feeding intensity of fish can be evaluated in real time. Compared with the traditional analysis based on two-dimensional image texture features, the method greatly reduces the amount of calculation task and provides an implementable scheme for the real-time measurement in aquaculture.The results show that the near-infrared depth image, which is not limited by the imaging conditions of the feeding site, can effectively represent the feeding behavior of fish.The method has ideal analysis effect for monitoring the fish that eat floating feed on the water surface and inhabit at the bottom of water body in non-feeding stage. This paper provides a new technical means for fish behavior analysis, which has positive guiding significance for the application of precision feeding.