Recently, in the pulp and paper industry, black liquor gasification (BLG) has been of interest as a potential replacement for the Tomlinson recovery boiler. Some commercial-scale BLG units have been developed. However, the full potential of high temperature gasifiers has not been realized because of the refractory failure. Computer simulation of existing materials will accelerate materials research in developing new refractory materials. A model based on continuum damage mechanics is presented to analyze the failure behavior of gasifier refractory lining under high temperature and chemical reactive environments by using the finite element method. This work provides a new methodology for the failure analysis of refractory material and would provide a powerful tool in the development of the high temperature gasifier refractories.