The performance and the fundamental weaknesses of asphalt mix under environmental temperature and water eects have made researchers try to modify the asphalt mix properties by using the proper additives. For this reason, this paper aims to improve the anti-cracking performance and water stability of asphalt pavement by adding a novel composite of diatomite and lignin fiber in asphalt mixes. Four types of asphalt mixes, including control asphalt mix (CAM), diatomite modified asphalt mix (DMAM), lignin fiber modified asphalt mix (LFMAM), and diatomite-lignin fiber composite modified asphalt mix (DLFMAM) were prepared in the laboratory. Low-temperature bending test, Marshall Immersion test, and freeze-thaw splitting test were employed to evaluate the performance of the asphalt mixes. Results reveal that the use of the lignin fiber in reinforced asphalt mixes combined with diatomite led to an enhancement in the asphalt pavement performance more than the other three types of mixes. Diatomite has an important influence on the water damage resistance of asphalt mix more than lignin fiber. On the other hand, diatomite has a small eect on the anti-cracking performance; meanwhile, lignin fiber showed a significant improvement in the cracking resistance of asphalt mixes. DLFMAM has the best traveling performances among all asphalt mixes. Thus, this work provides a good reference for the design of composite asphalt mixes.