The invention discloses a communication method of a railway vehicle network system, relating to the communication method and comprising the steps of carrying out an initial operation of a TCN (train communication network); mapping addresses of WTB (wire train bus) nodes as node indexes, wherein a node index sequence can describe relative positions of each WTB node; mapping the positions of the WTB nodes to actual positions of a vehicle; and completing communication between the WTB nodes by utilizing the WTB node indexes.