Abstract: Under deep peak regulation requirements, thermal power units face increasing flexibility demands while encountering operational challenges including flame deviation, uneven steam distribution, and overheating-induced tube bursts on heating surfaces. To ensure safe, stable and flexible unit operation, this study conducts detailed investigation of boiler water wall parameter distributions through an integrated coupling model incorporating combustion-side, steam-side, and heating surface wall temperature calculation modules. The model enables comprehensive coupled analysis of combustion processes, steam flow dynamics, and heat transfer characteristics. Combustion-side computations including fluid flow, combustion reactions, and heat transfer are performed using Fluent, while steam-side flow and heat transfer processes are calculated through user-defined functions (UDFs), with the heating surface serving as the interactive boundary for data exchange and iterative updates. Applied to a 1000MW dual tangential-fired boiler, the model demonstrates strong reliability with furnace exit oxygen content (2.53%), fly ash carbon content (2.61%), and water wall outlet steam temperature (744.59K) simulations closely matching measured values. The coupled analysis further reveals detailed distributions of heat flux density, steam temperature, heat transfer coefficients, and wall temperatures across the water wall, providing valuable reference data for enhanced boiler fault diagnosis and operational optimization under flexible operating conditions.