Based on the displacement of a ship lock foundation pit in the process of excavation，we apply the scheme and construction technology of prefabricated H-beam steel support in the reinforcement of deep soft soil foundation pit. In order to study the safety of prefabricated H-beam steel support with original double row pile support，we use the software of Lizheng 7.0 and GTS-NX to conduct modeling analysis，check the anti-overturning and overall stability of the reinforcement scheme and the axial force of the support，select a section of lock chamber foundation pit as the test section for construction，and compare the calculation results and monitoring results of excavation foundation surface. The results show that the overall stability of the reinforcement scheme and the axial force of the support satisfy the requirements of relevant specifications，and the development of horizontal displacement of deep soil can be controlled by using H-beam steel support.