The permeability of basalt fiber reinforced concrete(BFRC) is critical to the durability assessment of members after fire. The permeability test and pore structure change characteristics of BFRC under variable confining pressure after high temperature were studied. The evolution of permeability was analyzed as well under the same conditions by using confining pressure sensitivity parameters and dimensionless permeability. Results show that during confining pressure loading, BFRC permeability attenuates as a negative exponential function, and the initial permeability increases with increasing temperature after high temperature. Compared with reference concrete（RC）, the initial permeability of BFRC decreases by 4816%, 3389% and 157% after 100, 300and 600℃. According to confining pressure sensitivity parameters, the loading process of confining pressure is divided into sensitive zone, transition zone and insensitive zone, and the permeability of BFRC in sensitive zone decreases most with the increases of confining pressure. After confining pressure, pore structure of BFRC develops to small size pores and the number of pore decreases, resulting in lower permeability.