Abstract: When an over-flow condition occurs in a PWR nuclear power plant, the venturi flowmeter downstream of the make-up pump is required to form a cavitation-induced choked flow to protect the flowrate from exceeding the limit. Using the method of FLUENT numerical simulation and high-speed camera experiments, three different cavitation models were used to study the cavitation-induced choked flow phenomenon, cavitation development law and flow characteristics of the venturi tube. The results show that the ZGB cavitation model and the SST k-ω turbulence model can be used to simulate the cavitation flow limitation phenomenon of the venturi tube accurately. During the flow limitation, a periodic cavitation phenomenon will occur inside the Venturi tube. Under the action of the wall re-entrant jet, micro flow behaviors, such as small bubbles falling off, tail bubbles falling off and the whole vapor cavities falling off, will happen.