The invention discloses an acidized vermiculite. Main points of the technical scheme are as follows: ingredients of the acidized vermiculite are composed of expanded vermiculite, attapulgite clay, magnesium oxide, sulfuric acid, instant sodium silicate, polyvinyl alcohol, hydroxypropyl methyl cellulose and sodium carbonate; the ingredients of the acidized vermiculite are inputted into a grinding machine for milling; and a powder obtained after milling is the acidized vermiculite. According to the production method of the acidized vermiculite, acidification is carried out before composite dosing so as to avoid a chemical reaction between sulfuric acid and instant sodium silicate, polyvinyl alcohol, hydroxypropyl methyl cellulose and sodium carbonate; and after vermiculite is acidized, pH value is controlled within 5.0-7.0, and utilization rate of expanded vermiculite can be raised. The acidized vermiculite has good adsorptivity, thixotropy, thermal stability, plasticity and caking property. The acidized vermiculite is suitable for production of environmental protection materials, garden materials, building materials, foaming agents and fire products.