GaN-based　light-emitting　diodes　(LEDs)　grown　on　sapphire　substrate　have　current　transport　along　the　lateral　direction　due　to　the　insulating　nature　of　the　substrate,　and　the　anode　and　cathode　contacts　are　in　a　side-by-side　configuration.　The　resistance　of　the　n-type　material　of　the　GaN　and　the　lower　confinement　layer　is　not　negligible,　which　causes　the　current　to　crowd　near　the　edge　of　the　n-contact　pad.　The　current　crowding　problems　will　become　more　severe　for　large　area　and　high　power　devices.　In　this　paper,　the　current　spreading　effect　is　qualitatively　analyzed.　The　applied　current　density　and　the　effective　length　of　the　lateral　current　transport　are　found　to　have　a　considerable　effect　on　the　uniform　current　spreading.　Based　on　these　findings,　an　optimized　contact　scheme　of　high-power　GaN-based　LEDs　is　proposed　to　alleviate　current　crowding　effect　and　reduce　the　series　resistance　of　the　devices.　It　is　clearly　shown　that　the　high-power　GaN-based　flip-chip　LEDs　with　optimized　ring-shape　interdigitated　contact　scheme　have　a　relatively　uniform　temperature　distribution　by　measuring　the　surface　temperature　distribution　of　the　device　with　infrared　thermal　imaging　system.　It　is　confirmed　that　the　current　distributes　more　uniformly　over　the　contact,　and　current　densities　in　a　localized　region　of　the　device　are　reduced,　which　can　decrease　the　joule　heat　generated　and　improve　the　reliability　of　the　GaN-based　LED.