Super-deep T-shape diaphragm walls of Port Said East Container Terminal-Phase 2 Marine Works in Egypt are embedded in a two-layered stratum with soft upper and hard lower layers with high water head by sea. Because of more than 60 m depth of groove, the technology of trenching was crucial, and groove walls easy to collapse and its verticality insured more than 1/300 were two of momentous technical puzzles to be solved. Central equipments with hydraulic grab buckets and rotary drilling drivers were selected for the trench construction. In the process of trenching, some effective measures were adopted such as guide wall construction, groove walls advance reinforcement, mud of allocated proportion, liquid level controlling, etc., and momentous technical puzzles of trench construction were solved. Results show that the verticality of super-deep T-shape diaphragm walls is very well without its hole collapse. The trench can be finished with short time, low cost and good quality, and good social and economical benefits are gained.