According to the piezoelectric material damage theory and the fracture criterion based on damage theory, which has been established by Yang etc., reliability analysis is carried through about a damaged piezoelectric truss. Taken the mechanical damage extension force, electric damage extension force and cross-section area of bar element as stochastic variables, the expression of safety margins of bar element has been proposed. Based on those, the SFEM and PNET method are introduced to solve the reliability index of the structural system. The result indicates positive applied and negative applied electric field have great effect on the reliability of the system, which provides the basis to control the reliability of structural system. Finally, a calculation example is carried out under the conditions of positive applied electric field, negative applied electric field and no electric field. Meantime, the quantification results of the reliability index under three conditions are compared with each other.