In this paper, a magnetic core design with improved power performance for high power magnetic energy harvesting is discussed. As the power line generates H-field which is strong enough to make the magnetic core saturated, the magnetic saturation of core should be considered. We designed the magnetic core with consideration of saturation and connect harvesters in series for high power harvesting. In measurements, the output power with fifteen magnetic energy harvesters at 210 amperes power line current is approximately 1.14 kW.