Synaptosomes were isolated from pig brain by homogenization, differential centrifugation and sucrose gradient centrifugation. After synaptosome lysis in hypoosmotic buffer, the plasma membrane vesicles were collected. Following the solubilization of plasma membrane vesicles in Triton X-100, the solubilized protein was applied to calmodulin affinity chromatography column, and the delipidated plasma membrane Ca²⁺-ATPase was purified to nearly homogeneity. The novel feature of this purification is the use of large affinity column and heavy washing to facilitate the purified Ca²⁺-ATPase with higher activity and protein yield. The specific activity of the purified Ca²⁺-ATPase was recovered to a maximum of 3.32 μmol·mg^－1·min^－1 after incubation with asolectin. Silver staining of SDS-PAGE revealed a single protein band around M_r 140 000, showing the purity was over 90%. Different Ca²⁺ concentrations dramatically affect the specific activity of Ca²⁺-ATPase.