Thermal decomposition behavior and flammability of three polyarylates based on bisphenol A (BPA), 1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene (BPC II) and 4,4'-dihydroxy-3-ethoxy-benzylidenoacetophenone (Chalcon II), their copolymers and blends were investigated by pyrolysis GUMS, simultaneous thermal analysis and pyrolysis-combustion flow calorimetry (PCFC). The relationships between flammability and structure/composition of these polymers have also been explored. It is found that BPC II-polyarylate is an extremely fire-resistant thermoplastic that can be used as an efficient flame-retardant agent to be blended with the other polymers. Chalcon II-polyarylate is of interest as a UV/visible-sensitive polymer with a relatively low heat-release rate and a high char yield. PCFC results show that the total heat of combustion of the copolymers or blends changes linearly with the composition, but the change of maximum heat-release rate and char yield depends greatly on the chemical structure of the components.