Mercury-stannum　reactive　wetting　behaviors　were　studied　by　the　sessile　drop　technique　at　room　temperature,　and　wetting　surface　and　interface　were　also　studied　respectively　by　methods　of　field　emission　scanning　electron　microscope　(FESEM)　and　XRD.　It　showed　that　mercury　droplets　wetted　completely　on　the　stannum　substrate,　on　whose　surface　up-and-down　cellular　structures　were　generated,　and　two　metallographic　microstructures　of　intermetallic　compounds,　Hg　0.1Sn　0.9　and　Hg　1.25Sn　8.75,　were　produced　in　wetting　interface.