Cutter head swivel joint of small-diameter slurry balance shield machine

The invention discloses a cutter head swivel joint of a small-diameter slurry balance shield machine. The cutter head swivel joint comprises a flange long pipe fitting, a fixing piece used for installing an external pipeline, a connecting device, a front protection device arranged at the front end of the flange long pipe fitting and connected with a cutter head flange, and a driving device. A blocking mechanism is arranged in the front protection device. In the blocking state, the blocking mechanism blocks a channel, used for allowing a working medium to flow in, in the front protection device, and the working medium is prevented from flowing into the flange long pipe fitting from the front protection device. When a fault occurs and dismounting maintenance or part replacement is needed, isolation of a slurry bin and rear equipment can be achieved through the arrangement of the blocking mechanism, the self-adaptive protection isolation effect of the swivel joint is achieved, the operation process is convenient