The heat transfer of supercritical pseudo-boiling has been preliminarily studied, but the definition of gas-liquid interface is still not unified. The fluid-structure coupling numerical simulation of heat transfer characteristics in supercritical CO₂ pool is carried out by using laminar flow model. Platinum wire is the heating element, with diameter d = 70 μm. The heat flux density q_w is in a range of 0–2000 kW/m², and the pressure P is in a range of 8–10 MPa. Multi-scale mesh is used to model the heating wire, and simulation values accord well with the experimental data. The results show that due to the increase of the circumferential average Rayleigh number Ra_ave of the heating filament with q_w, the characteristic of the natural convection zone is that h increases with q_w. The temperatures of the four characteristic working conditions in the evaporation-like zone show a downward trend along the r direction. Through analogy with subcritical heat transfer and by calculating the thermal conductivity ratio Q_con/Q_t, the supercritical is divided into three regions, T < T_L is liquid-like region (LL), T_L < T < T_M is two-phase-like region (TPL), T > T_M is vapor-like region (VL). The rule is the same as that of x partition according to supercritical pseudo-boiling dryness. According to the curves of average thermal conductivity λ_ave and thermal resistance R_G versus heat flux q_w, determined by calculating thermal conductivity ratio, the variation law of heat transfer coefficient h with q_w in evaporation-like region can be well explained, as q_w increases, the thermal conductivity thermal resistance R_G increases, and the heat from the heating filament is difficult to transfer to the fluid outside the vapor-like membrane, leading the heat transfer coefficient h to decrease when q_A < q_w < q_C, and a significant increase in λ_ave when q_w > q_C, and the recovery of heat transfer when h rises again. In this paper, a new method of determining the gas-liquid interface of supercritical pool heat transfer is proposed. This method can effectively explain the heat transfer mechanism in the evaporation-like zone, and provide a theoretical basis for developing supercritical pool heat transfer in the future.