The invention discloses a mercury separating device for producing dental silver amalgam capsule products. The mercury separating device comprises a mercury storage tank, a first check valve and a mercury separator, wherein the mercury separator comprises a base and a mercury liquid cavity; an inlet of the mercury liquid cavity is connected to an outlet of a mercury output pipeline; a first outletof the mercury liquid cavity is connected to the upper end of a first branch pipe; the lower end of the first branch pipe is connected to a first inflow port in the upper side of a fourth branch pipe;a first outflow port is arranged in the lower side of the fourth branch pipe, and the first outflow port is connected to the upper end of a second branch pipe; the lower end of the second branch pipeis connected to the lower end of a third branch pipe; the upper end of the third branch pipe is connected to a second outlet of the mercury liquid cavity; the upper end of a fifth branch pipe is connected to a second outflow port in the lower side of the fourth branch pipe; an auxiliary hole is kept in the upper side of the fourth branch pipe, and the auxiliary hole is connected to an air branchpipe; a push rod is arranged in the fourth branch pipe; a through hole, which goes through the upper side and the lower side of the push rod, is arranged in the push rod, and the volume of the throughhole is a mercury using amount of one silver amalgam capsule; and via the pressing device, the push rod is driven to do reciprocating motions. With the application of the mercury separating device provided by the invention, production efficiency of the silver amalgam capsule products can be improved, technological processes can be reduced and labor cost can be reduced.