The invention relates to a LTCC substrate component and a eutectic sintering process method thereof. The LTCC substrate component comprises a LTCC substrate (2), a 0.08mm-thickness preforming silver tin soldering sheet (3), a fuzz button installing hole (a CNA8 high temperature protection resistance welding glue coating position) (4) and a LTCC substrate structure component (5). The LTCC substrate component is placed into an elastic positioning tooling (1) so as to form a product component. The component and the method are suitable for multiple sizes of special-purpose elastic tooling and substrate voidage can be increased to over 90% from below 80%; a protection technology of the fuzz button installing hole is designed so as to realize accurate protection to a welding process of different connector installing holes and subsequent connector installation is not influenced; and simultaneously, a silver tin soldering sheet is served as a welding material so that high precision control of a solder amount can be realized and product consistency is increased.