A　new　characterization　method,　namely　membrane　voltage　measurement　method,　is　proposed.　Because　the　recovery　time　of　membrane　potential　is　dependent　on　the　size　of　optoporation,　establishing　the　relationship　between　the　size　of　cytomembrane　optoporation　and　the　laser　energy　threshold　can　provide　theoretical　support　for　importing　different　exogenous　substances　into　cells.　In　this　study,　gastric　cancer　cells　are　cultured　with　gold　nanoparticles.　On　the　premise　that　cells　are　not　affected　by　the　toxicity　of　gold　nanoparticles,　gastric　cancer　cells　incubated　with　gold　nanoparticles　are　irradiated　using　a　nanosecond-pulsed　laser　with　different　energies.　Propidium　iodide　and　calcein-AM　are　used　for　staining　verification　of　perforated　cells.　The　results　indicate　that　optoporation　of　cell　membrane　can　be　successfully　achieved　with　400　nanoparticles　(diameter　of　100　nm)　per　cell　and　20　mJ/cm2　energy　density　by　532　nm　pulsed　laser,　without　obvious　dead　cells.　During　the　optoporation,　the　membrane　potential　is　measured　using　optical　mapping　technique.　It　is　found　that　the　membrane　potential　firstly　increases　and　then　restores　with　50　mV　maximum　increment　and　250　s　recovery　time.　These　results　confirm　that　the　cell　membrane　damage　can　be　recovered　by　optoporation　and　characteristiced　by　membrane　potential　change.　©　2020,　Chinese　Lasers　Press.　All　right　reserved.