During drilling operations， circulation of drilling fluid has to be stopped in make-up and break-up of drill rods， which will cause the cuttings to settle downhole and the equivalent circulation density （ECD） of the drilling fluid to fluctuate； thus affecting the borehole safety. In order to avoid the above situation， the concept of uninterrupted drilling fluid circulation drilling technology is proposed. Drilling fluid is diverted through a continuous circulation system （CCS） or continuous circulation joint （CCJ）， by-passing the section of the drill pipes being worked to maintain mud circulation in the well， and stabilizing the equivalent circulation density （ECD） of drilling fluid. According to the technical principle， an automatic drilling fluid uninterrupted circulation wellhead is proposed. Through the cooperation of back-up tongs， the automatic drilling fluid switching system and torque-transfer power slips， uninterrupted circulation of drilling fluid can be realized during the disassembly and assembly of single drill rods in drilling to avoid effectively the drilling safety problems caused by drilling fluid standstill and excessive settlement of cuttings .