Devices to replace cutting tools under pressure, devices to replace cutting tools from inside the cutterhead spokes with atmospheric pressure under the condition of ultrahigh pressure, configuration of equipment needed for operation under ultrahigh pressure, control standard for air permeability of tunnel face under ultrahigh pressure needed to access into the working chamber and replace the cutting tools, countermeasures to reduce the air permeability of the tunnel face, procedure of operation under ultrahigh water pressure, determination of the pressure of the compressed air needed to replace the cutting tools under ultrahigh water pressure and determination of modes of operation under ultrahigh water pressure are studied, in order to solve the technological difficulties in the inspection and replacement of the cutting tools in shield tunneling under ultrahigh water pressure. Conclusions are drawn that the operation principle of accessing into the working chamber and replacing the cutting tools under saturated air is similar to that of diving under saturated air and that the technologies presented in the paper are feasible. 