Under the condition of different choke pipe diameters, the choking-cavitator was made numerical analysis by Fluent software and the cavitation noise signals were tested. The effect of the diameters on the cavitation characteristics of chocking cavitator was investigated. It is shown that as the choke pipe diameters increases, the maximum pressure gradient will increase and the choked section will move to the choke pipe upstream. The numerical analysis on the choking-cavitator is consistent with the cavitation noise signals test results, and the best diameter is 10 mm.