Abstract: Taken the steam generator of Daya Bay Nuclear Power Station as the prototype, the “unit pipe” three-dimensional physical model of steam generator was established under the guidance of the similarity principle. Adopting Particle model and thermal phase change model, numerical simulation was implemented on two-phase flow and boiling heat transfer characteristics of the secondary circuit in steam generator based on CFX software. The results show that heat transfer coefficient and cross-section void fraction increase along the height of tubes at full load. The error of average heat transfer coefficient is 8.4% between numerical simulation and Rohsenow empirical correlation. The export mass fraction is consistent with the actual operating parameters of Daya Bay Nuclear Power Station. The successful application of thermal phase change model to two-phase flow numerical simulation of the steam generator can supply reference for thermal-hydraulic accurate analysis of the steam generator.