Implanted devices have important applications in biomedical monitoring, diagnosis and treatment, where intra-body communication (IBC) has a decent prospect in wireless implant communication technology by using the conductive properties of the human body to transmit a signal. Most of the investigations on implant IBC are focused on galvanic coupling type. Capacitive coupling IBC device seems hard to implant, because the ground electrode of it seemingly has to be exposed to air. Zhang et al. previously proposed an implantable capacitive coupling electrode, which can be totally implanted into the human body [1], but it lacks an overall characteristic investigation. In this paper, a comparable investigation of characteristics for implant intra-body communication based on galvanic and capacitive coupling is conducted. The human arm models are established by finite element method. Meanwhile, aiming to improve the accuracy of the model, electrode polarization impedance (EPI) is incorporated into the model, and the influences of electrode polarization impedance on simulation results are also analyzed. Subsequently, the corresponding measurements using porcine are conducted. We confirm good capacitive coupling communication performances can be achieved. Moreover, some important conclusions have been included by contrastive analysis, which can be used to optimize implant intra-body communication devices performance and provide some hints for practical IBC design. The conclusions also indicate that the implant IBC has promising prospect in healthcare and other related fields.