Abstract It has been proved that developing a supercaviting flow over under-water projectiles has an important role on their drag reduction, so many of researchers have focused on this subject during recent decade. In this research, the geometrical characteristics of supercavitaties developed behind three different conical cavitators with conic angles of 30, 45 and 60 degrees are studied numerically and experimentally. The experiments were done in an open-loop water tunnel. The fluid flow velocity in the test section was between 27 to 38 m/s. Also the 3D multiphase fluid flow over the cavitators within the test section are modeled and analyzed numerically by solving the corresponding governing equations using finite volume method and mixture model. Good agreement was observed in comparison between the numerical and experimental results. Finally, effects of some important parameters .i.e. the cavitation index, inlet velocity and conic angle of the cavitators on the geometrical characteristics of the supercavities are discussed