The variable area cavitating venturi is an effective means of thrust modulation for rocket engines. A two-phase model employing Schnerr and Sauer cavitation model and realizable k-ε turbulence model was developed in this paper to investigate the cavitating flow in the variable area cavitating venturi. The model was validated by comparison between computational and experimental data, and then was used to investigate the effect of the flow and geometric parameters on the performance of the variable area cavitating venturi. The discharge coefficient and critical pressure ratio were assessed. The results indicates that the upstream and downstream pressure have rare effect on the performance of the cavitating venturi, whereas the pintle stroke, pintle angle and throat rounding radius play a significant effect on the cavitating flow.