The utility model relates to the technical field of oil-gas mixing transportation, in particular to a tubular separation liquid slug capture device. The device comprises a base, a horizontal separator, a gas-liquid layering tube, a liquid collection tube and a gas collection tube. The horizontal separator is fixedly mounted on the base, a gas inlet connector is arranged on a casing on a top portion of the left side of the horizontal separator, a liquid inlet connector is arranged on a casing on the lower portion of the left side of the horizontal separator, the horizontal leftward gas collection tube is fixedly mounted on the gas inlet connector, and a blind plate is fixedly mounted at the left end of the gas collection tube. According to the tubular separation liquid slug capture device, the structure is reasonable and compact, the usage is convenient, the horizontal separator, the gas-liquid layering tube, the liquid collection tube, the gas collection tube and a communicating tube are matched for usage, pre-separation of gas and liquid phases is achieved and liquid slugs produced by oil-gas mixing transportation are effectively captured, vent valves and opening degrees of the vent valves are adjusted through a pressure sensor and a liquid level sensor, and impact and splitting phenomena cased to next stage treatment devices are avoided. The tubular separation liquid slug capture device has the advantages that the occupied area is small, the application range is large, and the separation effect is good.