The invention discloses an alloy liquid extrusion casting and forming device which comprises a liquid material chamber (1), a hammerhead (2), a sealing slide way (3), a pouring slot (4), a stationary workbench (71), a sealing cutter and an injection device (76). In the invention has the technical scheme, from bottom to top, an alloy liquid material is firstly injected under low pressure into a die cavity for mold filling, and then extruded under high pressure until the alloy liquid material is cooled, cured and formed into products in the die cavity. By adopting the technical scheme, the invention overcomes the defects of elaborate procedures, low efficiency, high cost, poor quality and great energy consumption existing in the prior art. The provided alloy liquid extrusion casting and forming device and a technical method thereof enable the alloy casting products to have perfect exhausting, no cold lap, sufficient casting, no flash, compact structure, fine and close crystal grain, high mechanical performance and high dimension precision as well as be subject to thermal treatment and welding. Thus, alloy liquid forming production achieves the purposes of high quality, high efficiency, low cost and low energy consumption.