The invention belongs to the technical field of shield machine lubrication condition monitoring, and proposes a shield TBM oil liquid state on-line automatic monitoring system. The proposed shield TBM oil liquid state on-line automatic monitoring system includes a planetary gear oil tank (1), a main bearing gear main oil tank (2) and an on-line monitoring acquisition control part (9); the on-line monitoring acquisition control part (9) has a plurality of solenoid valves (7); the plurality of solenoid valves (7) and a plurality of planetary gear oil tanks in a shield machine gear oil lubrication system are in one-to-one correspondence; the plurality of solenoid valves are cyclically opened in an on-line monitoring period, and only one is in a normally open state; the on-line automatic monitoring system is also provided with an oil liquid monitoring loop (5); the other ends of the plurality of solenoid valves (7) communicate with the oil liquid monitoring loop (5); and the oil liquid monitoring loop (5) is connected with the on-line monitoring acquisition control part (9). The shield TBM oil liquid state on-line automatic monitoring system provided by the invention ensures reliable lubrication of equipment and safe operation of a shield machine.