The invention discloses a construction method for preventing instability of a shield tunnel under high-sensitivity stratum conditions. The construction method comprises the steps of 1, arranging surface monitoring points, 2, installing grouting anchoring guide pipes, 3, determining grouting pressure and grouting amount, 4, grouting under pressure, 5, judging whether the surface is uplifted or not,6, judging whether the grouting pressure and the grouting amount reach design value or not, 7, troubleshooting, 8, stopping grouting under pressure and plugging a lifting hole and 9, one by one reinforcing tunnel segments of same rings which form a working surface in a tunnel section to be monitored. The deficiencies of synchronous grouting during shield tunneling under the high-sensitivity stratum conditions are effectively overcome, secondary filling is carried out at the backs of walls, the scope of grouting, filling and reinforcing of the backs of the walls of the tunnel segments is increased, the ability of the segments to withstand external forces is improved, and tunnel settlement deformation is resisted; and meanwhile, the grouting anchoring guide pipes can provide effective support force to lining segments, the overall stability of the shield tunnel is improved, and the risks of deformation and instability of the shield tunnel during construction and operation are effectivelyavoided.