Disclosed are a mold assembly for making alkali metal wax packets, a method for preparing same, and a method for using same. The mold assembly comprises a silicon substrate (10), the silicon substrate (10) comprising a mold isolator (11) at the edge of the silicon substrate (10) and a silicon substrate central portion (18). The upper surface of the silicon substrate central portion (18) is indented to form a plurality of wax packet receiving cavities (12). A cavity isolator (13) locates between adjacent wax packet receiving cavities (12). A release sacrificial layer (15) is formed on the upper surface of the silicon substrate (10), and a paraffin layer (16) is formed on the upper surface of the release sacrificial layer (15) away from the silicon substrate (10). Cavities (121) for containing alkali metal are formed on a side of the paraffin layer (16) away from the release sacrificial layer (15). The mold isolator (11) is provided with corrosion release holes (14). The mold assembly can reliably and controllably achieve batch production of uniform alkali metal wax packet arrays and is completely compatible with MEMS and microelectronic processes, with simple processes that can be easily implemented and high operability. The wax packet mold assembly can be reused, such that wasting of raw materials can be avoided, and the cost of batch production can be effectively reduced.