Different from traditional pixel array cameras, single-pixel imaging, as a new type of computational imaging technology, uses bucket detector without spatial resolution to detect light intensity reflected or transmitted by the target object, this intensity is calculated correlatively to the structured light intensity with specific spatial distribution modulated by mask patterns, and finally a clear object image is reconstructed. Single-pixel imaging has attracted widespread attention in scientific research circles because of its low cost and the ability to image in special wavebands. This article mainly discusses the signal-to-noise ratio of single-pixel imaging in different sampling methods, and describes imaging in special wavebands and experimental research of atomic and neutron imaging. Finally, in view of the disadvantages of single-pixel imaging in imaging time, ultra-fast imaging is discussed and expected to overcome the problem of long imaging time.