An ultrasonic apparatus has newly been developed to bond the fibrous assemblies. The system has low energy consumption and high productivity to bond the fibrous assemblies. By using the developed apparatus, we have evaluated the morphological structure and strength properties of the sample produced to make optimum processing conditions. In this study, the fiber used was 100% polyester(2.54, 62mm) and the samples were produced with the different levels of processing variables such as the number of ultrasonic treatment, web weight, horn pressure and feeding speed. As the result of SEM photographs for the ultrasonic nonwoven fabrics, it was found that polyester fibers between horn and anvil roller were melt by the frictional heat occurred to ultrasonic energy and thus the ultrasonic wave can be applied to consolidate the fibrous assemblies. In addition, we have found that the tensile and bursting strength of the sample were generally increased with increasing the number of ultrasonic treatments, horn pressure and web weight up to critical levels.