Abstract: Directivity pattern is one of the key indicators describing the radiated acoustic field.The displacement of flexural vibration of a thick plate is difficulty to obtain through the analysis solution.The directivity pattern of a thick plate with fundamental frequency at its flexural vibration has been calculated through numerical calculation.The results show that in terms of its fundamental frequency vibration mode,the directivity pattern with clamped boundary is the best,simply-supported better,while free boundary the poorest.In comparison with the thin plate,the directivity pattern of the thick plate is more acute.