Usually soft mattress and sand bags are respectively used in normal bottom protection engineering especially in shallow-water area.Because of the complexity of water condition in deep-water area,the quality of construction could not be controlled easily.We put forward an improvement technology by using soft mattress combined sand bags,and introduces the principle,construction process and quality control method according to the specific examples of projects.This technology has the advantages of high efficient,low investment and high quality in deep-water area which certificated by the measured data.