Based on the example of a new foundation pit in a phase II factory, the stress of the foundation pit construction with SMW construction pile supporting technology under the surrounding existing buildings was calculated and analyzed, and combined with the test results of foundation pit settlement, the stability of SMW construction pile under this construction condition was verified. The results show that the application of SMW pile supporting technology in the construction of wide foundation pit under complex construction conditions can effectively ensure the stability of foundation pit construction and ensure the construction quality.