In order to reduce the loss and improve the operating efficiency, it is necessary to optimize the operating schedule for the sources, grids and loads of active distribution network (ADN). Firstly, an operation model is established for source-grid-load interactive operation of ADN. In this model, the minimum loss is treated as the objective function, and the distributed generation sources, the tie-line switches of the grid, and the controllable loads serve as the optimized variables. Considering that the established model is about mix-integer nonlinear programming (MINLP) problem, the model is transformed into a bi-level combinatorial optimization problem to simplify the solving process. Finally, numerical tests are performed on the IEEE 33-node distribution network system, and results show that the proposed optimization method for the source-grid-load interactive operation of ADN can reduce the power loss and raise the operational efficiency.