It was found that the experimental result for electric conductivity of TiB
2-BN multiphase ceramics is consistent with the percolation model. The critical percent content of TiB
2 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 TiB
2 to BN after SPS sintering are in accord with those of the raw materials.