The invention discloses an inversion method for surrounding rock mechanical parameters of a large cavern group. The method aims at solving a bottleneck problem that the calculation in the inversion for surrounding rock mechanical parameters of the large cavern group through a stochastic global optimization algorithm consumes too much time. In the method, minimum errors of monitoring displacement and calculation displacement of surrounding rocks are employed as object functions, the FLAC 3D numerical simulation technology is employed, and a backtracking and searching - information vector machine cooperation optimization algorithm provided by the invention is also employed, so that the inversion, which consumes too much time on numerical calculation by one time, on the optimal value for the surrounding rock mechanical parameters of the large cavern group can be rapidly carried out. In practical engineering applications, compared with the parameter inversion directly performed through the stochastic global optimization algorithm, the value simulation reanalysis frequency in a parameter inversion process can be significantly reduced on the premise that a global optimal solution is obtained through the inversion method, so that the time for the parameter inversion can be effectively reduced. The method is quite suitable for the inversion of the surrounding rock mechanical parameters of the large cavern group, is efficient and rapid, and is easy and useful.