This study analyzes wireless transmission efficiency in magnetic resonance topology. In wireless power transmission systems, the overall efficiency is limited by the power consumption of coils. To improve the efficiency of wireless power transmission systems, this study proposes a suitable design for implantable devices by studying the shapes of coils, the distance between them, and the transmission media. Results show that efficiency declines as the distance between coils increases. Good efficiency is achieved under long-distance transmission when coils with large radii are used in transmitters. At short distances, small coils achieve better efficiency than large coils. The measurement results under an emulated human body experiment show that skin thickness is the key factor in transmission efficiency. The transmission efficiency under a pig skin thickness of 9 mm is 0.799% lower than that under the air medium.