In order to further improve the compactness of energetic powder materials， an ultrasonic-assisted isostatic pressing method is proposed， and an experimental prototype is designed and produced. The simulation software COMSOL is used to analyze the sound field of a single ultrasonic vibrator and the whole isostatic ultrasonic assisted molding system， and the influence of the cover thickness， 10 MPa pre-pressure and ultrasonic power voltage amplitude on the sound field distribution is studied. The simulation results show the rationality and feasibility of the ultrasonic-assisted isostatic pressing. The press molding experiments of polymer-bonded explosive（PBX） simulants are carried out whether to consider ultrasonic-assisted and 10 MPa pre-pressure conditions. The computed tomography（CT） and scanning electron microscope（SEM） are used to test and analyze the samples. The results show that the internal uniformity and compactness of the materials with ultrasonic-assisted and 10 MPa pre-pressure are better than those materials without， and their internal grains are finer and the grain distribution is more uniform.