Abstract: In order to clarify the joint acaricidal action of Ca2+ and scopoletin, provide theoretical proofs for the development and utilization of scopoletin, the synergism of Ca2+ to scopoletin on female adult mites, Tetranychus cinnabarinus, were studied by dipping method in the laboratory. The effects of Ca2+ and scopoletin on Ca2+-ATPase activities of T. cinnabarinus were also tested. The results showed that Ca2+ could dramatically improve the acaricidal activity of scopoletin against T. cinnabarinus, and the LC50 value of scopoletin combined with Ca2+ were reduced by 20% and 45% at 24 h and 48 h, respectively, compared with that of scopoletin used alone. The activities of Ca2+-ATPase decreased dramatically after being treated by mixtures of scopoletin and Ca2+ both in vivo and in vitro, but Ca2+ had no biological activity alone at the same concentration. The results also suggested that Ca2+-ATPase is one of the targets of scopoletin against T.cinnabarinus.