An inhalable nasal powder preparation of insulin and its preparing process are provided. The powder inhalation is consisting of self-emulsifying freeze-dried powder and pharmaceutically acceptable carriers. The dry powder comprises insulin, fat(s), emulsifier(s), antioxidant(s), supporting agent(s), bio-gel adhesive(s), and pH modifier(s), wherein the emulsifier is a mixture of lecithin and Tween 80, and the amount of fat in the formulation is determined by the surface area and the particle diameter of oil droplet.
