Abstract: This is an article in the field of ceramics and composites. In order to explore the resistance of basalt fiber to acid and alkali corrosion, basalt fiber with or without wetting agent was soaked in 3 mol/L sulfuric acid solution and sodium hydroxide solution, respectively, and the mass loss rate, fracture force retention rate and SEM image of fiber surface were tested. The results showed that with the increase of soaking time, the mass loss rate of basalt fiber with infiltrating agent increased from 1.42% to 7.33%, the fracture force retention rate decreased from 95.34% to 66.49%, the mass loss rate of basalt fiber without infiltrating agent increased from 3.69% to 9.40% and the fracture force retention rate decreased from 88.39% to 53.64%. After soaking in sodium hydroxide solution, the mass loss rate of basalt fiber with wetting-agent increased from 0.40% to 5.41%, the fracture force retention rate decreased from 97.37% to 79.82%, the mass loss rate of basalt fiber without wetting-agent increased from 1.50% to 7.08%, and the fracture force retention rate decreased from 93.42% to 69.85%. Both acid-alkaline corrosion cause fiber quality loss, increase fiber surface defects and reduce fiber breaking force.Sulfuric acid solution with the same concentration corrodes basalt fiber more seriously than sodium hydroxide solution. The soaking agent has a protective effect on the fiber and can slow down the corrosion of acid and alkali on the fiber.