The invention discloses a solid-liquid separation device and a solid-liquid separation method for analyzing the process of alloy solidification. The solid-liquid separation device comprises a supporting base, a separation vessel, a crucible, a top cover, a pressing rod, a pressing plate, and a filter screen; the supporting base supports the separation vessel to keep stable; the crucible is fixed in the separation vessel, and the crucible is used for containing an alloy sample; the pressing rod, the pressing plate and the filter screen compose a pressure-applying execution part; the top cover is arranged at the upper end of the separation vessel and covers the separation vessel to prevent the alloy sample from polluting a heating furnace; one end of the pressing rod passes through the top cover, the pressing plate and the filter screen, and the other end of the pressing rod is connected to applying equipment; under the drive of the pressure-applying execution part, solid-liquid separation is carried out on high-temperature molten alloy which reaches a specified temperature, and at the moment, the filter screen is in contact with the alloy sample in the crucible; and after solid-liquid separation, the solid phase and the solidified liquid phase are taken out after being cooled. The device disclosed by the invention has a reasonable structure, and is easy to operate, and by meansof the replaceable filter screen, solid-liquid separation in the alloy melting-solidification process can be efficiently and reliably carried out.