Abstract: It was found that the experimental result for electric conductivity of TiB₂-BN multiphase ceramics is consistent with the percolation model. The critical percent content of TiB₂ is 22.9% when the raw material granularity scale is related to this paper. The critical percent content will change with grain sizes, then results in the change in electric resistivity. The ratios of grain sizes of TiB₂ to BN after SPS sintering are in accord with those of the raw materials.