Variable area cavitating venturi (VACA) is one of core components for flow regulation in a delivery system. Flow coefficient is an important indicator to describe VACA flow performance. In this paper, six groups of experimental study were carried out to explore VACA flow coefficient variation. We measured flow coefficients at different Reynolds numbers by changing inlet pressure and valve opening. Study results show that flow coefficients are high when Reynolds numbers range from 20,000 to 80,000. With the growth of Reynolds number, flow coefficient shows a trend of increasing first and then decreasing. When Reynolds number is constant, flow coefficient is also affected by upstream pressure. By properly adjusting the upstream pressure and pintle stroke of VACA, the flow coefficient is avoided to be extremely small, thus ensuring that the VACA works in a better condition. The exploration of flow coefficients in this paper might shed light on the design and application of VACA.