In response to the complex working conditions of heavy cutter suction dredgers excavating sandstone mixed mudstone，this paper takes Qinzhou Port East Channel Expansion Project as an example to carry out construction technology research on the excavation and transportation of sandstone mixed mudstone soil by “Tiankun Hao” cutter suction dredger.Through comparative experiments between 7G and 8G six-arm cutter，the production efficiency and tooth loss of different cutter types are comprehensively compared，the dredging equipment is compared and selected.By analyzing and optimizing key construction parameters such as footage and cutting thickness during the construction，combined with the soil characteristics，the optimal excavation construction technology is determined.By analyzing and calculating performance of the mud pump，optimal control concentration for the transportation is determined.The construction technology optimization is carried out from two aspects of excavation and transportation，the construction technology of heavy-duty cutter suction dredgers for excavating sandstone mixed mudstone is summarized.The research results can provide reference for the construction of cutter suction dredgers under similar working conditions.