The invention relates to a source network coordination optimization method in economic dispatch, in particular to a method for bringing node splitting into an optimal dispatch decision A source network coordination optimization model for node splitting is established, and a heuristic solving method is adopted for solving the model. The solving method comprises the following steps: preparing data; determining a state adjustable set for nodes and branches; determining a set for nodes and branches according to power grid connectivity and an actual motion rule; carrying out optimal calculation according to the source network coordination optimization model for node splitting; according to the result of model optimization, adopting short-circuit current calculation and topology analysis to analyze a calculation tool, judging whether node short-circuit current and connectivity restraint is violated; if the optimized result does not violate operation restraint, outputting the calculation result; if the optimized result does not violate operation restraint, deleting the branches or nodes violating the operation restraint from a selectable set, and returning an optimal calculation step to carry out calculation again.