Body sensor network is a promising medical technology to address the overwhelming global aging issue, which requires advanced micro power sources with high energy density, long lifetime, small form factor and good biocompatibility. Potential micro power technologies include batteries, fuel cells, energy harvesters and supercapacitors, each of which have their own merits and demerits when applied in the body sensor network. Batteries such as dry battery and Li ion battery are currently the most mature product which has been extensively employed in the body sensor network research, but the improvement of their energy density is relatively sluggish due to the cumbersome material storage. On the contrary, micro fuel cells can achieve much higher energy density because of their lightweight fuel and oxidant, which can be refueled instantly when applied in wearable sensors. For implanted devices, both abiotic and biotic fuel cells can utilize the dissolved glucose in the body fluid as the fuel. As for energy harvesters, they can receive energy from both the external environment such as solar and radiofrequency, and the human body itself such as body heat and motion. Finally, supercapacitor is an effective energy storage component especially for energy harvesters, which can achieve excellent cycle stability.In general, the selection of micro power sources for the body sensor network should consider the specific requirement from the specific sensor node, so that a body sensor network with hybrid power supply is much more reliable than that with single type of energy supply. With the continuous development of different power technologies, the body sensor network is expected to be more lightweight, unobtrusive and reliable, leading to a low-cost and ubiquitous healthcare in the near future.