Apart from considering the routing of power lines， automatic routing of dispatching large screen for transmission network power flow diagram should be also added the name of lines， circuit breakers， real-time power flow values， as well as tag plate displaying status of main equipments， etc.， in order to highlight the readability of the whole diagram. A two phases solution for automatic routing， namely， sequential routing and optimal routing is proposed. Sequential routing includes corridor width assignment and regulation， outgoing lines placement surround the substation， lines routing according to discrete horizontal and vertical order of the position of substations， auxiliary placement as mentioned above. Optimal routing includes dismissing together with re-routing， integrated uniform placement adjustment. Two strategy categories， in name as protected dismissing and un-protected dismissing， compose the strategy storage of the search engines optimization method， in order to minimize the numbers of intersection of lines. Therefore， a good result in practical engineering applications has been achieved， due to the very detailed design of the automatic routing algorithm.