A high-purity inhalable insulin material, used for preparing a pulmonary pharmaceutical product, includes insulin particles having a particle size at the micrometer level and having the following characteristics : (i) the purity of insulin is not less than 96% on the dried basis; (ii) the total amount of insulin-related impurities is not more than 2%; (iii) the total amount of solvent impurities, which is not a co-solvent formulation component for a pulmonary product, is not more than 0.03%; and (iv) the total amount of non-solvent impurities is not more than 0.3%. Up to 99% by volume of the insulin particles in the inhalable insulin have a particle size of less than 5 μm, based on the total volume of the insulin particles. A high-efficiency method prepares high-purity inhalable insulin material. The yield rate for the high-efficiency method is 75 to 85% or more.