Out-To-in (O2I) body wireless communication is crucial for achieving personalized parameter modulation and ensuring reliable cardiac rhythm management in leadless cardiac pacemakers. Compared to traditional radio frequency (RF) wireless communication technology, magnetic resonance coupled human communication (MRC-HBC) technology is a promising method of O2I communication that utilizes human tissue as a conduction medium for electrical signals. In this paper, we present an O2I body communication method that combines low power consumption and high reliability for leadless cardiac pacemakers to enhance the performance of programmed management of leadless cardiac pacemakers (LCPs) and prolong the operating life of the pacemakers. Based on the dielectric properties of human tissues, a transceiver coil was designed for executing O2I body magnetic resonant coupling signal transmission. An O2I body multilayer electromagnetic model for finite element numerical computation was further constructed, and a chest phantom experimental platform was built for mutual verification. The results show that the highest channel gains of simulation and phantom experiment is-35.02 dB @ 13.56 MHz and-27.84 dB @ 13.56 MHz respectively, when the relative distance between the transceiver coils is in the range of 8-12 cm, which represents a significant advantage over the RF wireless communication methods used in previous studies.