The invention relates to a device for measuring content of gas in liquid metal. The device comprises a probe for immersing the liquid metal. The probe comprises a gas supply line, a gas collection part, a gas removal line, a gas loop, at least one gas detector, a gas movement device, a measurement gun and a rapid joint, wherein the gas supply line is opened at one end of the probe; the gas collection part is used for collecting gas and is provided with a diaphragm; the gas removal line is communicated with the gas collection part by fluid; the gas loop is provided with a first end and a second end; the first end is communicated with the gas supply line by fluid, and the second end is communicated with the gas removal line by fluid; the at least one gas detector is communicated with the gas loop by fluid; the gas movement device is communicated with the gas loop by fluid and enables gas to move; at least one part of the gas loop extends to pass through the measurement gun; the rapid joint is provided with two parts capable of being connected; the measurement gun comprises one part of the rapid joint; the probe comprises the other part of the rapid joint; the rapid joint provides gas tight connection of the gas supply line and the gas removal line and the first end and the second end in the gas loop in a connection state.