The invention relates to a coupling analysis method of a rod cluster subchannel and a critical heat flux mechanism model. The coupling analysis method comprises the following steps: firstly, setting the average heat flux qo of rod cluster channels, and calculating thermo-hydraulic parameters in the channels by adopting a subchannel analysis method; secondly, when the thermo-hydraulic parameters obtained through calculation in the step 1 reach a stable state, correcting and converting the obtained subchannel thermo-hydraulic parameters into a control volume of the critical heat flux mechanism model, judging a critical heat flux occurrence type, calling a departure nucleate boiling type or dry type critical heat flux mechanism model, and solving critical heat flux qCHF; and thirdly, judgingwhether critical heat flux can occur in the hottest channel, if conditions are not met, returning to the step 1 and modifying the preset average heat flux qo of the channels, and repeating the step 1and the step 2 until the conditions are met. The coupling analysis method provided by the invention has the advantages that the critical heat flux in the rod cluster subchannel can be effectively predicted, data dependency is reduced, application range is widened, and the coupling analysis method provided by the invention is significant on design and safety analysis of a reactor.