Abstract: By using the sessile drop method, the effects of active elements Ti and Zr on the wettability of the multicomponent Cu-based active filler metal on c-BN were studied.With the help of SEM, EDS and XRD, on basis of the key parameters theory, microstructure of the multicomponent Cu-based active filler metal were discussed.It can be found that the filler metal mainly consisted of Cu solid solution, Sn-rich phase as well as a small amount of intermetallic compound.By calculating the relation among the chemical affinity of elements, the influence mechanism of the wettability of the active element Ti, Zr in the multicomponent Cu-based active filler metal on c-BN was further elaborated.The results showed that the wettability of CuNiSnTi active filler metal on c-BN is better than CuNiSnZr.