Abstract: A type of circular multi-thruster plug nozzle has been designed,and its flow fields at different ambient pressures were simulated numerically by solving axisymmetric Reynolds-averaged Navier-Stokes equations with a finite-volume formulation.The simulations based on single equation and two equations turbulent models were compared.The results of the both models at proper mixing length were consistent in general.This type of plug nozzle embodies the main advantages of plug nozzles.