Research conclusions: The power SCADA system for passenger dedicated line is a star network in logic and can provides the converged service． As there are numerous power box － type substations along passenger dedicated line，point to point network program can not be adopted and the transmission bandwidth has to be converged． On considering the network mode of transmission system for passenger dedicated line and the communication requirement of power SCADA system，a tree structure network in physics while a star － type in logic should be established to transmit power SCADA system data with way of collection convergence in layers by using EPL and EVPL． With this program，the reliability of the system can be much enhanced and the cost can be much cut with the feature of convenient maintenance． It is the best choice for a communication network of power SCADA system for passenger dedicated line．