Abstract: In order to improve the damage diagnosis efficiency and reliability of BP neural networks, based on the fact that the number of the nodes in a grid structure is far less than that of the elements, the authors give the localization strategy of nodes oriented grid structural damage, i.e. the nodes related to damaged elements are used to denote the damage location of the elements and act as the output parameter of neural networks. Combined with a three-step damage diagnosis approach, a numerical planar truss damage diagnosis is carried out, and the results indicate that the method is practically available with significant effectiveness.