To improve the performance of InGaN-based visible light detectors ,a unilateral recessed interdigital electrode MSM-type blue light photodiode based on a GaN/InGaN MQWs epitaxial materialis fabricated and measured. The I-V characteristic measurement results of the device show that ,compared with traditional planar electrode devices ,recessed electrode devices have smaller and flatter dark currents and larger photocurrents with increasing bias. Spectral response measurements show thatthe cutoffband edge ofthe device is located near490nm ,and the rejection ratio at the band edge of the recessed electrode device is one order of magnitude higher than thatof the planar electrode device. At a bias voltage of 5 V ,the responsivity of the recessed electrode device is 0. 034 6 A/W @ 480 nm ,corresponding to an external quantum efficiency of8. 94% ,thatis higher than thatofthe planar electrode device. The improvementin device performance is attributed to the effective suppression of the surface conduction leakage current and the improved distribution of the built-in electric field achieved by the unilateral recessed electrode structure. Thisresultsin a reduced dark currentin the deviceand enhancesthe collection of photogenerated carriers by the electrodes ,thereby increasing the responsivity.