Food grade and medicinal potassium chloride are mainly prepared by further purification of industrial grade potassium chloride products.The industrial potassium chloride from salt lake is prepared by flotation agent,so there are some problems of residual flotation agent and some heavy metals exceeding the standard.By determination of industrial potassium chloride samples from salt lake,the mass fractions of ammonium and lead are 1.698×10^-4 and 1.63×10^-5.In order to prepare food grade potassium chloride,the activated biochar with the specific surface area of 147.26 m²/g and the iodine adsorption value of 297.5 mg/g was prepared by using pig bone as raw material and phosphoric acid as activator.Then,1 L potassium chloride solution was adsorbed by 10 g activated pig bone biochar and commercial carbon,respectively.Results showed that after the adsorption of activated pig bone biochar,the contents of all ions in the solution met the requirement of Food Additive Potassium Chloride,GB 25585—2010,and food grade potassium chloride was prepared successfully.