An algorithm is developed for the flow field in a two-phase cavitation region.The algorithm is implemented in a viscous calculation based on a Reynolds-Averaged Navier-Stokes(RANS) equation solver considering the effect of turbulence.A prior solution of wall detachment point and bubble length is not required.They are simulated by a cavitation model.The liquid/vapor interface is tracked and obtained by an iteration of flow field and interface updating.The algorithm is well validated with a comparison of computational and experimental data available for external flows of a cone/cylinder body and a hemisphere/cylinder body.The liquid/vapor interface shape and bubble length are calculated.The pressure coefficient distributions obtained along the cavitation bubble surface agree well with experimental results.The feasibility and accuracy of the algorithm are illustrated.