Conventional imaging systems based on lenses (groups) face inherent limitations such as cost, hardware size, and multifunctional applications. Lensless computational optical imaging system is a type of compact and lightweight minimalist multifunctional sensing architecture, which has been shown to be scientifically significant in a variety of fields, including biomicrography, multimodal imaging, and data security. This paper provides a concise overview of the fundamental principles, functional expansion, and intelligent reconstruction technologies underlying lensless imaging. By leveraging an"optical encoding+computational decoding"framework, this paradigm enables high-resolution, multimodal, and high-dimensional imaging, even under extreme conditions. The employment of sophisticated artificial intelligence algorithms has been demonstrated to result in a substantial enhancement of the quality of reconstructed images. This paper also discusses the potential for integrating lensless imaging and quantum intelligence technology, and anticipates its extensive applications in future endeavors, including high-security and multifunctional imaging.