In order to study on relationship between signal transmission detection and path length of communication link in human body communication（HBC）

on one hand

transmission characteristics of different transmission channels in the same human body model are studied

on the other hand

the transmission characteristics of same-named transmission links（links whose transmitter and receivers sensors are in the correspondingly same positions） among different models are studied.According to the lateral and longitudinal comparisons

the analysis shows that channel transmission characteristics bear positive correlation with path length.This correlation can be put in this way that signal transmission path loss goes up with the increase of transmission path length and the analysis also shows that this correlation is true in non-straight propagation.