The existing hyperbaric operation technologies in tunneling by largediameter slurry shields under complex hydrogeological conditions and complex environment have some disadvantages In the construction of Weisanlu rivercrossing tunnel in Nanning, China, the shield boring has to be suspended to perform repair and maintenance of the cutterhead As a result, the technology of saturated hyperbaric operation under compressed air is proposed In this paper, the geological conditions of the tunnel where the shield stops are studied on basis of the geological prospection report, the working principle of saturated hyperbaric operation under compressed air is presented, the calculation of the pressure at the tunnel face in introduced, and the forming of the airtight filter membrane, the equipment and working procedure of saturated hyperbaric operation under compressed air are expounded The practice shows that the mentioned technology can ensure the successful inspection and replacement of the cutting tools of shield machines under complex conditions, and it can improve the adaptability of shield machines to complex geological conditions