The invention relates to a preparation method of a silver-based brazing filler metal for brazing high-volume-fraction SiC particle reinforced aluminum matrix composites. The purpose of the invention is to solve the problems that brazing filler metals within the temperature range between 565 DEG C and 585 DEG C do not exist in the field of electronic packaging at present and that the strength of weld joints is low. The method includes the following steps: (1) Ag-Cu-In-Sn-Ti alloy balls which are uniformly mixed are prepared; (2) oxide layers are removed, and the balls are broken into alloy blocks; (3) the alloy blocks are put into a quartz tube with a bottom slot, so that a quartz tube loaded with the alloy blocks is obtained; (4) the quartz tube loaded with the alloy blocks is put into the heating induction coil of a melt-spun furnace, and high-purity argon is filled after vacuumization; (5) when the Ag-Cu-In-Sn-Ti alloy blocks in the quartz tube are heated to melt, argon is utilized to blow the melted brazing filler metal out of the bottom slot of the quartz tube, the melted brazing filler metal sputters onto a copper roller, so that a strip is thrown out, and after cooling, the silver-based brazing filler metal is obtained. The preparation method is mainly used for preparing the silver-based brazing filler metal.