The circular diaphragm wall was adopted for the enclosure structure of the rolling machine room at the Shijiu port area of Rizhao Port. This paper expounds the difficulties on construction of the circular diaphragm wall at the port in the dredger fill formation environment, such as collapse of the thick sand layer, small inner diameter and large radian of the wall, the circular steel cage, trench deviation. Some treatment measures have been adopted, including ground reinforcement, setting up external expansion angle for the guide wall, improvement of the excavation method, fabrication of the special processing platform, deviation rectifying with multiple methods. Good results have been obtained, providing some references for similar projects.