Icing and ice accumulation on blades or cooling apertures in aero-engines along with other mechanical systems present significant hazards to operating efficiency and structural integrity. Porous structures enhance fluid flow and modify thermal conductivity. Therefore, this study examines droplet spreading and heat transfer on subcooled porous surfaces, modelling the interactions between droplets and porous structures based on the multiphase flow-phase field method coupled with a heat transfer module. The model's accuracy and reliability were validated by comparing experimental results with numerical simulations. The dynamics of droplets on porous surfaces are examined in detail, focusing on the influence of Weber number, while emphasizing its effect on the coupled heat transfer during impact on subcooled porous structures. It is found that increasing the Weber number markedly enhances droplet dynamics, resulting in a larger spreading factor and an increased tendency for icing, accompanied by pronounced secondary heat transfer effects, which modify the local heat flux distribution during the impact and solidification processes. When the Weber number increases from 60 to 160, the peak heat flux is observed to increase by approximately 90%. In addition, the reduction in surface wettability leads to distinct penetration and heat transfer modes of the droplet. Specifically, the peak heat flux is lowered by roughly 3% compared with the normal wettability conditions, and no pronounced secondary heat transfer behavior is observed. These results provide theoretical insights into droplet icing behavior and support the development of more effective anti-icing strategies.