The invention discloses a preparation method of low-salt-content low-fat-content air-dried chickens. The preparation method of the low-salt-content low-fat-content air-dried chickens comprises the following steps: slaughtering live broilers, removing the feather, carrying out eviscerating, and carrying out blanching so as to obtain naked chickens; and then, orderly carrying out pickling, air-drying, feather picking, cooking and packing. A step of de-salting and de-fatting is also included between the step of carrying out air-drying and the step of carrying out feather picking; and the de-salting and de-fatting method comprises the following steps: Step S1, preparing wet mud, namely weighing 35-45 parts of modified food-grade diatomite, 15-25 parts of food-grade gypsum powder, 6-8 parts of food-grade silica gel and 3-5 parts of food-grade alginic acid, parts by weight, carrying out uniform mixing and stirring, adding 90-110 parts of water, and then, carrying out uniform stirring; Step S2, uniformly coating the wet mud on the surfaces of the air-dried naked chickens, carrying out air-drying in an air-drying workshop at a temperature of 8-18 DEG C and a relative humidity of 25-75% until dry mud is formed on the surfaces of the naked chickens, wherein the air-drying time is 15-25 hours and 400-600 grams of the wet mud is applied on per 1 kilogram of the naked chickens; and Step S3, removing the dry mud on the surfaces of the naked chickens so as to realize de-salting and de-fatting. The air-dried chickens provided by the invention are obviously reduced in salt content and fat content, so that the air-dried chickens are good in taste and healthy.