Abstract: An algorithm based on object-oriented(00) method is proposed.All pipe components in network topology structure are given special object,properties.Hydraulic calculation models are expressed by object methods.Boundary conditions variations are reflected by object events.Then hydraulic calculation can be solved as traversing all pipe components.Two cases are calculated and analyzed.It indicates that the method can effectively handle hydraulic imbalance caused in structure or in heat sources of a multi-source looped-pipe network with small deviations.