The study investigates the nuclear state boiling heat transfer characteristics of deionized water and CNT/water nanofluids using the VOF-DPM model in CFD. The VOF method is utilized to handle bubble behavior in the continuous phase, while the DPM model simulates the impact of suspended nanoparticles on heat transfer during phase change. Analysis of simulation results focuses on bubble behavior in nanofluid phase change heat transfer, flow field behavior near the heating surface caused by bubble growth and detachment, and a comparison with deionized water to understand the enhanced heat transfer mechanism of nanofluids. Numerical simulations demonstrate that adding CNT nanoparticles to water enhances the boiling flow field strength near the heating surface, promoting bubble detachment and improving heat transfer efficiency. The high thermal conductivity of CNT enhances the thermal conductivity of the liquid and enhances the heat conduction so that the liquid can warm up faster, and finally, due to the irregular movement of CNT nanoparticles can weaken the heat transfer boundary layer and reduce the thermal resistance of heat transfer enhances the heat transfer.