The chapter presents the theoretical foundations and study of the principles of construction of an automated complex for reproducing an alternating magnetic field. The results of studies of instrumental errors of the automated complex and ways to reduce them, as well as methods and means of improving the efficiency of the complex for reproducing an alternating magnetic field are presented. The stability parameters are determined and estimated. Methods for calculating stability parameters are considered. Particular attention is paid to the structural features of the construction of an automated complex for reproducing an alternating magnetic field, increasing its efficiency and evaluating the accuracy of reproducing magnetic field parameters. The methods and means of verification of an automated complex for reproducing an alternating magnetic field, the current state of metrological support of the means of reproduction of alternating magnetic fields of various forms are considered and investigated.