The invention relates to automatic control system and method of flow control among district heating networks. The invented system controls return temperature of district heating network. The system contains pressure difference controller (26), which is connected to supply (2) and return (6) pipes, in addition connected to a programmable controller (17) and a network pump (9). The method has to be realised as follows: local thermostatic valve set (12h) for local heating provides a signal to the programmable controller (17) which afterwards receives temperature difference change between supply (2) and return (6) pipes and sends a command to network pump (9), controlled under the proportional pressure method, thereby improving energy efficiency performance of the system by matching heat energy generated by source (15) to dynamic end-user demand for heat energy.