Analysis of the dynamic function of neural circuits is the focus and difficulty of current brain science research. Recently, miniaturized microscopic imaging technologies provide important research tools. Compared with two-photon fluorescence imaging and fiber photometry, miniaturized microscopic imaging systems can perform long-term, subcellular resolution, real-time imaging in freely moving animals. In the past ten years, scientists have successively developed wearable one-photon and multi-photon imaging systems with high stability. In order to improve performance and expand applications, they continuously optimized systems from the aspects of probes, optoelectronic components, data transmission and etc. In this paper, we will analyze and discuss the imaging principle, basic structure, system optimization, application scheme, and future development of miniaturized microscopic imaging systems. We summarize the research progresses in various directions, aiming to provide a reference for technology improvement and application expansion of neuroscience.