The invention discloses a low-carbon low-phosphorus nickel-chromium-iron alloy used for stainless acid resistant steel, which is characterized by comprising the following components in weight percent: 12 to 70 percent of nickel, 3 to 12 percent of chromium, less than 0.5 percent of carbon, less than 0.3 percent of sulphur, less than 0.035 percent of phosphorus, less than 2.5 percent of silicon and the balance of ferrum. The invention is mainly suitable for alloying stainless acid resistant steel. The alloy has low carbon and low phosphorus, which can effectively relieve the load of decarburization in the steel-making process, greatly prolongs the pulverization period of the alloy and meanwhile is beneficial to the production demands of clean steel.