Abstract: The feldspar was one of the major impurity mineral in purification process of high purity quartz. In this article the feldspar which was separated and enriched from a granitic pegmatite quartz ore was selected as research object. A serial of comparative studies on leaching effect of the feldspar or roasting product with different treatment process including conventional roasting, chloridizing roasting, one-step leaching and three-stage leaching were conducted. Finally, the roasted product and leaching residue were characterized by XRD and SEM for finding out the mineral transformation characteristics of the feldspar in different treatment process. Leaching results showed that the maximum weight loss rate of 70.27% which means the optimal leaching effect was obtained, when the process that the feldspar roasted in chlorine gas atmosphere at 1130 ℃ followed by three-stage leaching by 15 g/L HCl+5 g/L HF mixed acid solution was adopted. Results of XRD and SEM analysis showed that the K element in feldspar would partly be gasified and removed by chloridizing roasting. When the high concentrated mixed acid was adopted, the mineral structure of feldspar was easier to be destroyed and the higher leaching rate of Al was obtained, but the leaching rate and removal effect of K was limited by cubic silosilicite phase which was formed newly by K⁺ and SiF₆^2- in the leaching process.