The invention provides a construction technology of a tunnel soft rock large-deformation section, and relates to the tunnel construction technologies. The construction technology of a tunnel soft rocklarge-deformation section mainly solves the problem that dangers are prone to occurring in the current construction process of a large-deformation section. Advance geology forecasting is conducted byadopting TSP and geological radar method and an advance geological drilling method and a deepening hole detection method; the construction of an advance middle pipe shed comprises the steps of hole arrangement, hole forming, pipe inserting, opening sealing and grouting; the construction of an advance small guiding pipe comprises the steps of hole arrangement, hole forming, pipe inserting, openingsealing and grouting; then preliminary bracing is conducted by taking the following measures of a hollow anchor rod, a mortar anchor rod, a reinforcing mesh piece and a steel frame; and finally concrete jetting is conducted. The construction technology of the tunnel soft rock large-deformation section has the advantages that the construction safety and quality can be ensured, and the constructionperiod is short.