Abstract: The disclosure belongs to the field of tunnel construction technologies, and more particularly, relates to a construction method for making a water-rich sand layer shield over cross an existing line and underneath cross a sewage push pipe at a close range. The method specifically includes the following steps of: S1) before construction, using MIDAS GTS NX software and FLAC3D to optimize a tunneling scheme antecedently by numerical simulation to determine a part of unfavourable stress; S2) tunneling a test section, the test section being a stratum crossing a front shield direction by 45 m to 60 m; and S3) performing shield crossing construction, wherein a shield crossing construction process includes the steps of: 1) controlling a soil pressure; 2) controlling a shield thrust; 3) performing synchronous grouting; 4) performing a ballasting measure in a tunnel; and 5) performing automatic monitoring in the tunnel.