Abstract: The regulatory effect of Ca2+ on ethylene biosynthesis in plants is related to action site. The extracellular Ca2+ can maintain cell membrane permeability, inhibit ethylene production, and delay senescence; however, when excess Ca2+ enter into cytosol, the cytosolic Ca2+ promotes ethylene production and induces senescence. The endogenous calmodulin(CaM) is closely correlated with ethylene production, and involves in ethylene metabolism and the effect of exogenous hormone on ethylene production. In addition, Ca2+ is indispensable to ethylene signal transduction in plants.