The wet method is used to roughen the GaP layer on the AlGaInP-based red LED surface and deposit the ITO on the roughened GaP surface. The effect of roughening time on the surface morphology of GaP is studied. Scan electron microscopy(SEM),semiconductor wafer tester, X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) are used to characterize the morphology,optical and electrical characteristics,interfacial orientation and elemental properties of the LED devices. The brightness of the LED before and after coarseni ng and changes in the photoelectric properties are analyzed.The test results show that the HI O₄,I₂,HNO_3series roughening solution can effectively increase the light output angle through the GaP surface and the ITO interface at room temperature,and the roughening time of 30s can improve the li ght emitting efficiency of the AlGaInP LED by 21.4%.At the same time,the defect density at t he interface is increased,which leads to the Fermi level away from the valence band ,resulting in a forward voltage increase of 0.04V and dominant blue shift of wavelength of 0.36nm.