Abstract: Heterotrimeric G proteins are classes of signal-transducing proteins that bind to guanine nucleotides and possess GTP hydrolase activity. G proteins are composed of three subunits α, β, and γ, and are considered as the "molecular switch" in the GPCR signaling pathway. The abnormal activation of G protein is strongly related to diseases such as uveal melanoma, asthma, et al., making directly targeting G protein as an promising strategy for combating diseases. In this review, the classification and physiological functions of G protein are briefly described, and the research progress of G proteins in diseases, G protein modulators are reviewed.