The occurrence of porous deposits on the core surface during the operation of a pressurized water reactor can seriously affect its heat transfer characteristics and increase the surface temperature of the cladding. Continued heat transfer deterioration causes subcooled boiling and boron enrichment within porous deposits, leading to axial power anomalies in the core, and the study of porous deposits is beneficial to improving the economics and safety of reactor operation. In this paper, a two-dimensional boiling unit model of a porous deposits was established using COMSOL software to couple heat conduction, darcy flow, solute transport and chemical reactions in a multiphysics field to reasonably predict the temperature field, velocity field, boric acid concentration distribution, and PH distribution within the porous deposits. On this basis, the influence of different parameters (porosity, boiling unit radius of porous deposits, heat flow density) on the maximum effective thermal conductivity, the pattern of thermal parameters (temperature, superheat, percentage of subcooled boiling, and saturation temperature) on the chimney boundary are analyzed. The results show that localized superheating, maximum boric acid concentration and subcooled boiling occur at the bottom of the porous deposits. There is a negative correlation between the porosity and the percentage of subcooled boiling area, and a positive correlation between the radius of the porous deposits and the heat flow density and the percentage of subcooled boiling area.