The　breakdown　voltage　of　a　gas　insulated　gap　under　a　non-uniform　electric　field　can　be　increased　by　inserting　a　barrier　due　to　extending　the　arc　development　path,　which　is　of　great　potential　to　be　applied　to　environmentally　friendly　gas　insulation　system.　In　this　paper,　the　AC　breakdown　voltages　of　different　air　insulated　point-plane　gaps　with　polycarbonate　barriers　of　different　sizes　were　experimentally　investigated.　Every　case　was　tested　for　20　times.　The　breakdown　voltages　with　the　point　radius　of　1-5　mm　and　gap　distance　of　2-5　cm　were　obtained.　In　addition,　the　effects　of　barrier　size　under　different　conditions　were　compared.　The　electric　field　distributions　in　the　inter-electrode　gap　were　analyzed　by　a　finite　element　method.　It　was　found　that　the　AC　breakdown　voltages　of　the　considered　hybrid　gas-solid　insulation　system　have　a　close　relationship　with　the　non-uniform　coefficient　of　the　electric　field.