Abstract: this paper proposes an artificial neural network (ANN) based feeder loss calculation model for distribution system analysis. In this paper, the functional-link network architecture to derive the various loss calculation models for feeders with different configuration. Such artificial neural network is a feedforward network that uses standard back-propagation algorithm to adjust weights on the connection part between any two processing elements (PEs). Feeder daily load curve on each season are derived by field test data. Three-phases load flow program is executed to create the training sets with exact loss calculation results. A sensitivity analysis is executed to determine the key factors included power factor, feeder loading, primary conductors, secondary conductors, and transformer capacity as the variables for components located at input layer.