The invention belongs to the technical field of metal surface hardening treatment. The invention discloses a bran-new low temperature ion nitriding method for austenitic stainless steel to solve the problem that in a conventional low temperature ion nitriding method for the austenitic stainless steel, the thickness of a nitrided layer is thin or nonuniform after the surface treatment of the austenitic stainless steel. The method comprises the following steps: (1) putting an austenitic stainless steel workpiece into an ion nitriding furnace, and evacuating the air to form a vacuum in the ion nitriding furnace; (2) conducting an ion bombardment by filling argon gas into the ion nitriding furnace; (3) conducting low pressure ion nitriding and high pressure ion nitriding by filling nitrogen and hydrogen into the ion nitriding furnace. According to the method, the nitrided layer with a certain thickness and a uniform thichness can be formed on the surface of the austenitic stainless steel, so that the austenitic stainless steel is good in hardness and wear-resisting property while the original corrosion resistance is maintained.