Ball valve, a rotational motion valve uses ball shaped disk. It is used for on/off or throttling operations. It offers the minimum resistance to flow. To investigate the valve performance and its characteristics, the flow through the valve is studied using numerical technique. In this paper the numerical simulations were performed using commercial code FLUENT, to study the flow patterns and to estimate the valve sizing coefficient, torque coefficient and cavitation index for investigation of cavitating flows. These simulations were performed at different pressure drops and for varying percentage opening of the valve.