InGaN/GaN　MQW　blue　light　emitting　diode　(LED)　structures　whose　p-GaN　cap　layers　were　grown　with　various　flow　rates　of　Cp2Mg　and　p-GaN　films　with　the　same　growth　conditions　were　grown　by　MOCVD.　The　LEDs　were　fabricated　and　characterized　by　I-V　measurement　in　order　to　investigate　the　effects　of　this　varied　growth　condition　on　the　electrical　character　of　the　devices.　As　the　Cp2Mg　flow　rate　increased,　the　forward　voltage　of　the　LEDs　decreased　at　first　and　then　increased　at　a　certain　Cp2Mg　flow　rate,　and　the　leakage　current　increased　without　discontinuity.　It　was　found　that　low　Cp2Mg　flow　rate　can　lead　to　low　hole　concentration　and　poor　electrical　property　of　the　p-GaN　cap　layer,　but　high　Cp2Mg　flow　rate　made　the　situation　even　worse,　the　surface　morphology　and　crystallinity　of　the　films　become　rough　and　worse.　This　was　responsible　for　the　changes　of　the　electrical　character　of　the　LEDs.