In-situ resource-based construction technology can greatly reduce the cost of lunar surface base construction and realize high-quality operation and maintenance. How to make full use of in-situ resources to prepare high-performance building structure materials has become a hot topic in current research. In this study, geopolymers are prepared by lunar regolith simulant and reinforced with basalt fibers to enhance the mechanical properties of the materials. Exploring the effects of strong/weak alkali solutions and basalt fiber content on damage patterns, mechanical properties of lunar regolith simulant. The results of the study showed that the incorporation of basalt fibers changed the damage pattern of lunar regolith simulant and increased the deformation capacity of lunar regolith simulant. Under the condition of strong alkali solution excitation, the optimal content of basalt fiber was 0.2%; under the condition of weak alkali, the optimal content was 0.1%. The compressive and flexural strengths of the lunar regolith simulant tended to increase and then decrease with the increase of fiber content. Compared with the strong alkaline environment, the basalt fiber content had a more significant effect on the lunar regolith simulant in the weak alkaline environment.