Abstract: In order to study the microstructure characteristics of basalt fiber reinforced foam concrete and the influence of different fiber content on its damage characteristics, this paper carried out X-CT test and uniaxial compression acoustic emission joint test on basalt fiber reinforced foam concrete with density grade of 1000 kg/cm³. Based on Avizo image processing and acoustic emission basic parameters and b_i values (Improved b value), the microstructure characteristics of fibers and pores and the damage evolution characteristics of materials were analyzed. The results show that the addition of basalt fiber can effectively improve the mechanical properties of foam concrete. The average compressive strength of the specimens with 0.5vol%, 1.5vol% and 2.5vol% fibers increase by 1.37 MPa, 4.58 MPa and 2.77 MPa, respectively. The fiber fractal dimension of the specimen with 2.5vol% content is mainly in the range of 1.0-1.3, the fiber agglomeration is obvious, the fiber angle is concentrated, and the performance of the specimen is reduced. After adding basalt fiber, the trend of acoustic emission b_i value of the specimen is gentler, and basalt fiber can effectively inhibit crack development.