By starting from an analysis on the typical architecture and features of power dispatching automation systems

a testing model is proposed

which is more in keeping with the actual characteristics

and some theorems are also proved based on the model. It is proved that the inputoutput (I/O) space of a largescale software can be significantly reduced by proper decomposition according to the relationships between different software modules and the correlations between input factors and output factors

laying a theoretical foundation to simplify the testing of power dispatching automation systems.