The invention provides a vacuum low-pressure casting forming device for a titanium alloy component. The vacuum low-pressure casting forming device for the titanium alloy component comprises a device body, a vacuum low-pressure casting pneumatic control system and an electronic control system. An upper chamber and lower chamber type structure is adopted by the device body, a water-cooled copper crucible is arranged in a lower chamber, a casting mold is arranged in an upper chamber, an intermediate separation plate is arranged between the upper chamber and the lower chamber, and a liquid lifting pipe is arranged on the intermediate separation plate. The vacuum low-pressure casting pneumatic control system is connected with the device body, a vacuum system and a protective gas source system, and digital combination valves are adopted as flow regulation actuators. The electronic control system is composed of an industrial control computer and a PLC. After the smelting process of titanium alloy is completed in a smelting chamber, the water-cooled copper crucible is lifted to a casting position through a lifting device, an upper chamber and lower chamber intercommunication valve is closed, the flow of protective gas fed into the lower chamber is controlled through the computer, the pressure difference between the upper chamber and the lower chamber is established, the liquid alloy is filled in the casting mold through the liquid lifting pipe under the action of the pressure difference, and the casting process is completed. Compared with traditional centrifugal casting and bottom leakage type suction casting, the mold-filling capacity and solidification feeding capacity of the titanium alloy can be improved, castings with better casting quality and thinner wall thicknesses can be obtained, and a new means is provided for batch production of minitype titanium alloy components.