Low melting point aluminum based filler alloys are widely used in the connection of aerospace. In this study, prepare to metal powder for ultrasonic system. The research can be divided into three parts:(1) Discussion on low melting point aluminum-based fillers.(2) Design verification on the ultrasonic horn.(3) Low melting point aluminum based filler is prepared by ultrasonic atomization method. The research shows:(1) the low melting point aluminum -based filler have rich Si, Al2Cu, eutectic Al-Si-Zn and eutectic Al-Cu-Zn phase. When the content of Cu and Zn is higher, the hardness value is higher. (2) curve design analysis, ultrasonic horn can magnify the displacement of vibration, and improving to the atomizing. (3) A low melting point aluminum-based filler powder capable of less than 74 μm.