The goal of our research is to develop a method for synthesis of active shielding systems of power frequency magnetic field generate by high voltage power lines, which allows to reduce the magnetic field level to sanitary norms. The synthesis is based on the solution of a multi-criteria stochastic game, in which the gain vector is calculated on the basis of the Maxwell equations solutions in the quasi-stationary approximation. The equilibrium state of the game is based on the stochastic multiagent optimization algorithms by multiswarm particles. The objective of the synthesis of the active shielding system is to determine their number, configuration, spatial arrangement, wiring diagrams and compensation cables currents, setting algorithm of the control systems.