With the development of dredging,suction dredging soil is more and more complex.Existing equipment and traditional excavation technology of trailing suction dredger cannot safely dredge soil containing H2S toxic gas.To solve this problem,the existing ship is protected and reconstructed,and the targeted construction technology is formulated.The protective measures has been adopted including mud tank protection,work and living accommodation protection and staff personal protection.The advanced construction technology is adopted for example selecting the wind direction when construction,thin layer excavation,alternating construction,full tank replacement.The construction task of dredging soil containing H2S toxic gas is successfully completed in Namibia Walvis Bay project.