In the article, based on the developed methods of calculating the magnetic field and synthesis active screening system of the magnetic field of transformer substations, the possibility of mitigation the induction of the magnetic field to the level of sanitary standards in a living space located near a transformer substation with a power of up to 100 kVA using the active loop. The substantiation was performed theoretically on a computer model and experimentally on a laboratory model of a transformer substation and an active shielding system. The synthesis of active screening system of the magnetic field of a transformer substation with a power of 1260 kVA was carried out, and the possibility of mitigation the induction of the magnetic field in a living space to the reference levels by means of an active screening system with four active loops. A comparison of the efficiency of the developed systems of active screening of the magnetic field of transformer substations with known methods of passive shielding and methods of improving the design of transformer substations was carried out. For the first time, the sufficiency of using passive shielding methods for the power of transformer substations up to 300 kVA, methods for improving the design for the power of transformer substations up to 600 kVA and the method of active shielding for the power of transformer substations up to 1260 kVA are substantiated. The method of active shielding is universal and allows you to mitigate the magnetic field without interfering with the design of the transformer substation. Recommendations for the use of magnetic field mitigation methods in living spaces from built-in standard transformer substations with a power of 100–1260 kVA have been developed.