Abstract: The study of order degree and structural temperature of K-feldspar can provide significant information about the forming physicochemical conditions of deposit. Infrared spectroscopy is used to test the K-feldspar phenocrysts from the mineralized porphyry in the Weilasituo polymetallic deposit. The result shows that the order degrees range from 0.85 to 0.95, with triclinities of 0.7-0.9. The structural temperatures are 547.17-578.36℃, suggesting that the K-feldspar phenocrysts are microcline. It is confirmed that the K-feldspar is a product of hydrothermal alteration.