Abstract: Refractory lining is a key component of the Opposed Multi⁃Burner (OMB) coal⁃water slurry gasifier. The drastic temperature change in the gasifier will cause the refractory lining to generate great transient thermal stress， which will cause the refractory lining to crack or even peel off.In order to improve the service life of the refractory lin⁃ ing，it is expected to observe the performance of the refractory bricks in situ.However，the extreme environment in the gasifier makes it difficult to study its interior through online testing and experimental methods.Through the nu⁃ merical simulation method，it is possible to study some problems encountered by the refractory lining during the opera⁃ tion of the gasifier without being restricted by extreme conditions.Taking a certain OMB coal⁃water slurry gasifier as the object，a finite element analysis model of the refractory lining at the K⁃brick was established.The influence of material parameters with temperature variation was considered comprehensively.The transient temperature field and stress distri⁃ bution in the refractory lining during the refractory preheating， start⁃up and parking stage were calculated and analyzed.The results show that the heat flow is gradually transferred from the hot surface brick to the steel shell dur⁃ ing the refractory preheating process of the gasifier.Due to the hysteresis in heat transfer，the overall temperature field of the refractory lining needs another 60 h to reach a steady state when the hot face brick temperature reaches 1 300 °C .For all the calculation conditions， the maximum thermal stress of the structure occurs at the top bend of the hot face brick. The transient stress field of the refractory lining is consistent with the temperature field， indicating that the magnitude of the thermal stress is related to the temperature gradient，the greater the tempera⁃ ture gradient， the more dramatic the change in thermal stress. The tensile stresses generated during the stopping and cooling of the gasifier are the direct cause of cracks in the refractory lining.During the frequent opening and stop⁃ ping of the gasifier，the refractory lining is constantly subjected to the interaction of tensile and compressive stresses， which is the fundamental cause of its fracture.The operating temperature should not be too high during the start⁃up and parking of the gasifier，and the operating temperature should be kept as low as possible while ensuring the normal oper⁃ ation of the gasifier.The numerical simulation results further provide an effective reference for the optimization of the working conditions and safe and stable operation of the refractory lining of the gasifier.