The invention provides an etching technological method for hard light aluminum foil. The method comprises the steps of pretreatment, primary alternating current etching, intermediate treatment, secondary alternating current etching, chemical cleaning, aftertreatment and high-temperature treatment. A phosphate buffer protection agent is added into a solution for secondary alternating current etching, the length of an electrode plate is increased. The etching efficiency is improved, meanwhile, reaming is more uniform and reasonable, and the specific volume of the etched foil is further improved on the premise that the mechanical performance of the etched foil is ensured.