Deep and ultra-deep drilling has become the key direction of oil and gas exploration and development research at the present stage. The density window of deep and complex formations is narrow, and most of the wells drilled are high temperature and high pressure wells, which have a large impact on the density and rheological parameters of drilling fluids and further affect the stabilization state of the wall of the well after the intrusion of drilling fluids into the formation. Therefore, this paper comprehensively applies the knowledge of heat transfer, applied mathematics, and computer science to analyze the temperature change of the whole well section and the change of physical properties parameters of drilling fluids in deep formations, and judging the degree of wall instability by introducing the wellbore yield state parameter, and carrying out the simulation and analysis of wall stability in drilling wells of deep and complex formations, and optimizing the design of the selection of the performance parameters of drilling fluids in the subsequent wells.