The invention discloses a vacuum gas-liquid separating device. The vacuum gas-liquid separating device comprises a cylinder, an exhaust material-blocking block, a vacuum tank, a separator and a vacuumliquid storage tank. A fusion material cavity is installed in the cylinder. The air inlet end of the exhaust material-blocking block is connected to the cylinder, and the air inlet end is communicated with the fusion material cavity. A vacuum cavity is installed in the vacuum tank, the side wall of the vacuum tank is connected with an exhaust pipe communicated with the vacuum cavity and used forconnecting with a vacuum extractor, and the bottom end of the vacuum tank is connected with a transition plate communicated with the vacuum cavity and the exhaust material-blocking block. The separator comprises a support column and a spiral plate, the support column is fixed at the bottom end of the vacuum tank, and the spiral plate is spirally coiled on the support column along the circumferenceof the support column. A vacuum liquid storage cavity is installed in the vacuum liquid storage tank, and the vacuum liquid storage cavity is communicated with the bottom end of the vacuum cavity through a connecting pipeline. The gas and liquid are separated from a volatile substance by the vacuum gas-liquid separating device. The vacuum extractor is prevented from corroding and blocking by thevolatile substance, the service life of the device is improved, the product quality is improved, and the production cost is reduced.