Abstract: The characteristics of heat treatment weight loss and corresponding pyrolysis products of LC were determined using an TG-FTIR analysis system. The results show that the beginning temperature of pyrolysis is at 100-120 ℃. When heated to 500　℃, more than 90% of the LC is decomposed, and there is a single weight loss peak during the heat treatment process. Aerobic conditions were conducive to rapid response to heat treatment for LC and easy generation of black residue. In anaerobic conditions, the pyrolysis productsof LC were mainly hydrocarbons and organic compounds which comprised functional groups such as benzene or phenyl, CO and so on. Aerobic conditions are conducive to the generation of CO₂ and CO as well as other organic compounds which were comprised of functional groups such as phenyl, carbonyl, aryl and so on. Thereaction temperature of TFT-LC is lower than that of TN-LC and STN-LC.