According to the power load to the power supply reliable request and the interrupt power supply in politics, the economy causes the losses or the influence degree, has the interrupt power supply will cause person casualties, significant political influence, significant economic loss, of a power load public place order grave disorder situations, is called the important load. The important load's nature cannot cut power, therefore uses the double power source power supply in the actual movement, when a power source breaks down, another power source should not simultaneously receive the damage, and can transform the power supply, to the important load's management, can reduce even in arises suddenly in matter's loss, does not affect its power supply situation. Is the modern power supply enterprise implements the modernization to the distribution network, the scientific management, enhances the power supply security, one of reliable essential auxiliary means that to important load management key point work, both has assured the security, reliable power supply, and saved the public outlay, has made the contribution for the national construction. what this article introduced is when shoulders the double power source moves is importantly normal, the single power source or loses the electricity to need to report an emergency on the software, when therefore has the simulation operation, how in the network analysis situs to judge the current on-off operation whether to affect in the network the important load power supply situation. the main design proposal is: ⑴The establishment graph part and indicated with its correspondence's data that completes the graph part with its data expression 11 corresponding relationships, has established the graph and the data relation. ⑵The establishment graph part model and the node leg model's mapping relations, simultaneously also showed that how when to carry on the graph operation, how part's incidence relation to transform the graph model to the node leg model, and its incidence relation record in matrix. ⑶Based on the tree search method analysis, judges on-off operation whether to cause the important load distortion. key word: The important load, the network analysis situs, the power source distorts, double power source, simulation operation