The invention relates to a method for preparing CIGS powder and belongs to the technical field of photovoltaic material preparation. The method includes the steps that a copper source, an indium source, a gallium source and a selenium resource are mixed according to a certain proportion for ball milling, and the obtained mixture of copper, indium, gallium and selenium is placed in a vacuum sintering furnace for solid-phase synthesis under protection gas; the mixture is cooled to room temperature and taken out for grinding and screening, and the CIGS powder is obtained. According to method for preparing the CIGS powder, the copper powder adopted in the raw material powder is nanometer powder, low-temperature short-term synthesis can be achieved, the solid-phase synthesis stage is facilitated, and energy consumption is lowered; the synthesis process is simple, easy to operate and low in cost, and large-scale industrial application is facilitated.