Because the traditional measuring method is not suitable for the layered settlement monitoring in soft soil foundation of the constructions under water,such as beach protection embankment project,the new type of measuring instrument and technique were proposed for the safety monitoring problem of layered settlement in soft soil foundation under water of Manyusha beach protection embankment project.To avoid interrupting the construction,keep instruments well running,and obtain the compression of soft soil foundation,new instruments were installed on site for the prototype monitoring test.According to the monitoring result analysis,the process rules of the layered settlement and compression of the soft soil foundation under water were obtained during construction and running.It showed that the soft soil foundation of the beach protection embankment under water was safe and stable.The feasibility and applicability of the new instrument and technique for the layered settlement monitoring in soft soil foundation of the constructions under water were tested and verified.