Alkali-activated coal gangue-slag (AACGS), carbon fiber (CF) and steel fiber (SF) were used to prepare CF-AACGS-based and SF-AACGS-based conductive mortars. The effect of fiber type and fiber content on the mechanical properties and resistivity of mortar were investigated, and the conductive of mortar at different water content and ambient temperature was discussed. The results showed that the 28-day flexural strength of the mortar was increased by 67.66% and 80.78% when 0.45 vol% CF alone or 2.0 vol% SF alone was added, respectively. And the compressive strength was improved. At 0.3 vol% CF or 1.5 vol% SF, the spatial conductive network was formed inside the mortar and the percolation threshold was reached, resulting in lower resistivity. And the effect of water content and ambient temperature on its conductivity was significantly reduced.