 Intracellular liquid-liquid phase separation, LLPS, is a critical process involving the dynamic association of biomolecules and the formation of non-membrane compartments, which plays a vital role in regulating biomolecular interactions and organelle functions. Optical imaging methods have been used to study LLPS, including fluorescence microscopy, super-resolution microscopy, and two-photon microscopy. These techniques enable visualization of the dynamics of LLPS and the distribution of fluorescent probes within cells. Future developments in optical imaging technology may be able to further elucidate the mechanisms of LLPS and its implications in disease progression. This article was authored by Shofeng Zhang, Hao Yangli, Yu Ma, and others.