To reveal the highlyefficient heat transfer mechanisms in the vapor mushroom region of saturated nucleate pool boiling, a newmodel was developed in which three heat transfer mechanisms were considered: the conduction and evaporation in the microlayerregion underneath vapor stem, the conduction and evaporation in the macrolayer region between the vapor mushroom and theheater surface and Marangoni convection in the macrolayer region. Two-dimensional conservation equations for laminar flow in themacrolayer region and conduction in the heater were solved. The SIMPLE-algorithm was used for handling the pressure-velocitycoupling. Calculated boiling curve agrees well with the published experimental data and numerical results showed that about 60%heat flux is transferred byevaporation in the microlayer region, and about 40% heat flux is evaporated at the vapor-liquid interfacesof the macrolayer due to both the conduction and Marangoni convection heat transfer in the macrolayer region. Further investigationswere also carried out for the cases in which onlyone or two heat transfer mechanisms were considered to assess the relativeinfluences of the microlayer evaporation and Marangoni convection.