The invention discloses a method for improving extended wavelength gallium indium arsenide detector etching damage which is provided with a whole set of chip preparation etching processes. The methodincludes the steps: (1) depositing a mask etched by silicon nitride; (2) performing heat treatment in the nitrogen environment; (3) transferring table top images; (4) etching an N groove; (5) forminga table top; (6) removing etching damage. The method has the advantages that the mask etched by the silicon nitride is deposited, the heat treatment is performed in the nitrogen environment, materialdamage can be repaired, complex center density is reduced, material quality is improved, dark current of devices is reduced, hole carrier density can be increased, P-electrode ohmic contact stabilityis facilitated, resistance is reduced, a table top forming process includes gas is etched by the aid of chlorine methane, hydrogen decomposed by the methane in the plasma etching process can passivatedangling bonds formed by etching, and non-radiative recombination center density in materials is reduced. According to an etching damage removing process, damage layers of etching surfaces can be removed, the non-radiative recombination center density is reduced, subsequent passivation effects are enhanced, and the method is applicable to preparation of a high-performance short wave infrared gallium indium arsenide detector.