GCaMPs are new genetically encoded calcium indicators based on a single fluorescent protein molecule with high calcium affinity. The fluorescence intensity of GCaMPs is proportional to intracellular calcium concentration. GCaMPs can be easily targeted and expressed in specific cells and cellular compartments, so as to make it possible for observing calcium-mediated signal transduction. GCaMPs can provide long-term in vivo imaging of calcium signals during development, disease, and drug therapy, making them promising tools for physiological, cytobiological and clinical studies.This paper summarized the principle, progression and application of GCaMPs, hoping to introduce a new calcium detection tool for further exploring the behavior and functions of cells under physiological and pathological states.