Abstract This paper investigates the mechanical and fracture properties of basalt fiber reinforced fly ash geopolymer concrete with different length (3 mm, 6 mm, 12 mm and 18 mm), which were tested by means of compressive strength test, splitting tensile strength test and three point bending test. The fiber reinforced mechanism was characterized by SEM. Simultaneously, the strain field and displacement field of FAGC were explored by using of digital image correlation. The results reveal that the addition of basalt fiber improve compressive strength, splitting tensile strength, peak load, fracture toughness and fracture energy, and all of them for fiber reinforced FAGC with 6 mm were biggest. In addition, a decrease in crack length and an improvement in relative COD increment for basalt fiber reinforced FAGC before the load level of post-80% peak load were observed.