Objective To observe the protective effect of Xinhani against mitochondria injury induced by exogenous Ca~(2+).Methods Isolated mitochondria was prepared from brain of rats.The concentration of free Ca~(2+) in mitochondria,the activity of mitochondria and MPT were measured respectively in the presence of Ca~(2+) at different concentration without or with Xinhani.The swelling of mitochondria represented by OD values at 540 nm.Results AS compared with that of control group,Ca~(2+) concentration of mitochondria was increased significantly(P0.05 or P0.01) respectively when incubated with CaCl_2,decreased the activity of mitochondria(P0.01),MPT induce swelling of mitochondria and OD values at 540 nm of mitochondria suspension decreased.OD values at 540 nm of mitochondria suspension could manifest the change of swelling of mitochondria(P0.01);Xinhani reduced significantly Mca increase induced by CaCl_2(P0.01),and reduced the activity of mitochondria(P0.05 or P0.01),OD values at 540 nm of mitochondria suspension were increased by Xinhani(P0.05 or P0.01).Conclusion Exogenous Ca~(2+) could increase the concentration free Ca~(2+) in mitochondria,leaded to opening of MPT and decrease the activities of mitochondria.Xinhani could protect mitochondria from damage induced by exogenous Ca~(2+).The protection effect of Xinhani on mitochondria may be one of the important mechanisms of protective effect against cerebral damage caused by ischemia reperfusion.