The disclosure relates to the field of vacuum monitoring, and discloses an online monitoring system for a vacuum degree of a vacuum container, which comprises a vacuum cut-off valve, a vacuum gauge, asignal output line and a vacuum local digital display meter; wherein, the vacuum cut-off valve is in a normally open state during measurement and is used for enabling the vacuum gauge to communicatewith a vacuum interlayer of the vacuum container; the vacuum gauge is used for measuring the vacuum degree in the vacuum interlayer; the signal output line is used for transmitting vacuum degree datameasured by the vacuum gauge to the vacuum local digital display meter; and the vacuum local digital display meter is at least used for displaying the vacuum degree. The online monitoring system of the invention has the beneficial effects that: the vacuum gauge is used for realizing local meter monitoring of the interlayer vacuum degree, the vacuum degree data of the container interlayer can be monitored in real time, and whether a low-temperature liquefied gas storage container meets the quality standard requirement or not is judged according to the vacuum degree data, so that the discharge waste of a discharge device and the occurrence of potential safety hazards caused by abnormal vacuum degree are avoided; at the same time, repeated plugging and unplugging operations of the vacuum gauge can be avoided, and the service life of the vacuum gauge can be greatly prolonged; in addition, remote monitoring can be achieved.