Abstract: Small modular reactors (SMRs) hold significant potential for application in the context of ‘dual carbon’ and are important for achieving a low-carbon energy transformation and revolutionizing energy technology. Compared to conventional light water reactors (PWRs and BWRs), SMRs exhibit significant differences in core design, primarily characterized by lower operating power, lower pressure, lower flow velocity, lower core height, and more irregular power distribution. These factors introduce additional challenges and complexities in the study of the critical heat flux (CHF) mechanism for SMR fuel assemblies. In this paper, the development of CHF mechanism model, empirical relationship and subchannel analysis program were reviewed. The characteristics and difficulties of small modular light water reactor CHF research were analyzed. Taking NHR200-Ⅱ, an integrated full power natural circulation small pressurized water reactor developed by Tsinghua University as an example, the key methods of critical heat flux analysis were introduced.