Previously the authors developed and protected by a patent a new monitoring system based on the dependence of relative permeability of ferromagnetic mediums on acting stresses. The aim of this work is testing this monitoring system in natural conditions and determining convergence of deflected mode values received by system and theoretically calculated. The results of complex examination of St. Trinity Church (the city of Balakovo) are presented in the given work. As a result several variants of tightening reconstruction were suggested and calculated. Results of theoretical and experimental determining deflected mode of basic variant of tightening with using new monitoring system were considered. Divergence of results of theoretical calculation and actual instrumental data did not exceed 5%.