Abstract: The uniformity of GaAs/InGaP heterointerface after wet etching by citric acid and HCl based etchant was studied experimentally in this work.The surface morphology and roughness of GaAs/InGaP heterointerface under different etching conditions were investigated with atomic force microscopy（AFM）,etch step measurement and electron microscope.A simple and effective method is found to get good etching quality.