For evaluating the reliability of topology of district heating network,connectedness between heat sources and heat users was proposed based on spatial network model.Four indices of connectedness reliability were established to describe heat supplying from heat sources and heat flowing into heat users.The connected-ness importance of pipe was then put forward on the basis of the connectedness reliability from all heat sources to all users.The connectedness reliability of heating network with multi-sources and multi-loops was analyzed,as well as the connectedness importance of pipes on main pipelines,loops and common pipelines.Analysis shows that the connectedness reliability of heating network with multi-sources and multi-loops was considera-ble.The closer the distance between pipe and source,the higher the connectedness importance of pipe.The length of the main pipe is important to the system reliability.