Ghost imaging is an active indirect imaging technology based on second-order or high-order correlation of light field. It has the characteristics of high sensitivity and strong anti-interference ability, and has important application value in biomedical imaging, remote sensing imaging, ocean detection and other fields. However, the sampling time is long and the imaging speed is slow due to the requirement of sampling number in the process of ghost imaging. Achieving high quality image reconstruction under the condition of low sampling is still one of the problems that need to be solved in the practical application of ghost imaging. In addition to the detailed description of the principle of ghost imaging, this paper introduces the progress of low-sampling ghost imaging in recent years, such as the theoretical and experimental results of deep learning-based computational ghost imaging, and summarizes and prospects the application of ghost imaging.