Crack resistance and thermal performance are the critical properties of ceramsite lightweight aggregate concrete used in building wall panels. To study the influences of ceramsite pre-wetting time and basalt fiber volume content on the crack resistance and thermal performance of basalt fiber ceramsite concrete, the axial compressive strength, elastic modulus and thermal conductivity tests of basalt fiber ceramsite concrete were carried out in this paper, and the elastic strength ratio and thermal conductivity were used as indicators to evaluate the crack resistance and thermal performance of basalt fiber ceramsite concrete. The results show that both ceramsite pre-wetting and basalt fiber increase the thermal conductivity of concrete, but its thermal performance still meets the specification requirements of ceramsite concrete for the external walls of public buildings. When the volume content of basalt fiber is 0.2% and the pre-wetting time of ceramsite is 72 h, the thermal conductivity of concrete specimen is 0.100 2 W/(m·K) and the elastic strength ratio is 1 109. While meeting the requirements of thermal performance, the crack resistance of concrete specimen increases the most, the increase rate is 19.5%. Based on the existing conversion formula model of concrete elastic modulus and axial compressive strength, a modified model suitable for basalt fiber ceramsite concrete is proposed, and the correlation coefficient is 0.905 7.