This study conducted the three-point bending tests to examine the flexural performance of the basalt textile reinforced alkali-activated slag-fly ash mortar after elevated temperature exposure. The influence of surface coating with the epoxy resin, number of textile layers and matrix type on the high-temperature resistance of basalt textile reinforced mortar specimens was also investigated. The experimental results indicated that the flexural strength of basalt textile reinforced alkali-activated slag-fly ash mortar specimens decreased almost linearly with the increase of temperature due to the deterioration of the matrix and basalt textile. And the failure morphology was also transformed from multiple-cracking mode to single-cracking mode. After heat exposure at 800 ℃ for 1h, the remained flexural strength of the specimens was only 1.67 MPa. Surface coating with epoxy resin enhanced the flexural strength under the exposure temperature below 600 ℃. Due to the decomposition of epoxy resin and the deterioration of the bond between fiber and matrix, significant strength loss can be observed when the exposure temperature was higher than 600 ℃. Compared with the basalt textile reinforced Portland cement mortar specimens, the alkali-activated mortar specimens owned better high-temperature resistance, and less strength loss under the exposure temperature above 400 ℃. An increase in the number of textile layers can enhance the mechanical properties of specimens after exposure to elevated temperatures to a certain extent, but the enhancement gradually weakened with the increase of temperature. And the improvement to the flexural bearing capacity became insignificant for the epoxy coated specimen after the exposure temperature reached 600 ℃.