<p>Laminar flow separation caused by shock wave-boundary layer interaction is a critical issue for supersonic vehicles, which significantly affects their aerodynamic performance. In-depth studies of the flow separation characteristics and accurate predictions of the separation zone dimensions are essential for optimizing flow control strategies and determining the location of the peak heat flux. This study focuses on the incident shock wave flat plate model and employs direct numerical simulation to investigate the separation flow caused by an incident shock wave-laminar boundary layer under varying shock intensities and wall temperatures. The research results show that with increasing shock intensity, a&#xa0;secondary separation zone appears within the separation region, and the emergence of this secondary zone increases the normal pressure gradient of the primary separation zone. The size of the secondary separation zone first increases, then decreases, and ultimately vanishes as the wall temperature increases. Additionally, based on the Katzer prediction formula, the separation bubble dimension prediction formula was optimized by considering the effects of wall temperature. Experimental and numerical validations demonstrate that the optimized formula can predict the scale of the primary separation zone in the Mach number range of 1.6–15 and wall temperature ratios of 0.2–1. The formula exhibits excellent predictive accuracy under both adiabatic and isothermal wall conditions and remains reliable in accurately predicting the primary separation bubble dimension even in the presence of secondary separation.</p>