The traditional strengthening for disease concrete structures under water is building a cofferdam, then draining and rehabilitating. The defect of the method is taking time and costly. for this reason, the paper presents a new under water rehabilitation technique of disease concrete as follows: (1)grouting to concrete crack; (2) chiseling the face of old concrete under water in order to rough it; (3)rooting reinforcement net flat in old concrete; (4) pouring non dispersive concrete under water. The technique mentioned above is much better than the traditional method. The new technique was used at first for concrete crack rehabilitation of Huangsha port sluice in north coast of Jiangsu. By field testing, it shows that mechanical properties of non dispersive concrete poured under water meet the design criterion. Meanwhile, it is proved that old and new concrete are conjoined firmly, and the integrality of concrete structure is resumed effectively. So, the rehabilitation technique of disease concrete under water has notable economic and social results.