Abstract: Objective To establish a rapid and economic method for isolating human peripheral blood eosinophils with high viability for patch-clamp studies and investigate the electrophysiological properties of Ca²⁺-activated K⁺ channel of the isolated cells. Methods Peripheral blood eosinophils were isolated by modified discontinuous Percoll density gradient centrifugation,and the electric currents in the single Ca²⁺-activated K⁺ channels of the cells were recorded using patch-clamp technique with cell-attached configuration. Results The purity of the eosinophils from healthy donors reached (90.5±1.6)%,with a viability rate over 99% and recovery rate of (48.2±6.9)%.The isolated cells were morphologically intact,from which Ca²⁺-activated K⁺ channel activity could be detected. Conclusion The peripheral blood eosinophils isolated using this rapid,simple and highly efficient method are characterized by high purity and viability without obvious cellular injuries,which are ideal for patch-clamp studies.