In this paper,several questions associated with discontinuous boundary elements are discussed.1.The optimum position of collocation point is reevaluated and it is found that accuracy of integrals,especially the nearly singular integrals, is the key factor that influences the accuracy of discontinuous boundary element analysis.2.Discontinuous boundary element is employed for combination of FEM BEM coupling procedure.The patch test, devised by Lu et al,is reconsidered. It is demonstrated that coupling procedure by discontinuous boundary element can achieve results of high accurary.