Alzheimer’s disease (AD) is a specific neurodegenerative disease. This study adopts single-chain variable fragments (scFvs) as a potential immunotherapeutic precursor for AD. According to the remarkable effects of monoclonal antibodies, such as the depolymerization or promotion of Aβ42 efflux by Crenezumab, Solanezumab, and 12B4, it is attractive to prepare corresponding scFvs targeting amyloid-β-42 protein (Aβ42) and investigate their biological activities. Crenezumab-like scFv (scFv-C), Solanezumab-like scFv (scFv-S), and 12B4-like scFv (scFv-12B4) were designed and constructed. The thermal stabilities and binding ability to Aβ42 of scFv-C, scFv-S, and scFv-12B4 were evaluated using unfolding profile and enzyme-linked immunosorbent assay. As the results indicated that scFv-C could recognize Aβ42 monomer/oligomer and promote the disaggregation of Aβ42 fiber as determined by the Thioflavin-T assay, the potential mechanism of its interaction with Aβ42 was investigated using molecular dynamics analysis. Interactions involving hydrogen bonds and salt bonds were predicted between scFv-C and Aβ42 pentamer, suggesting the possibility of inhibiting further aggregation of Aβ42. The successfully prepared scFvs, especially scFv-C, with favorable biological activity targeting Aβ42, might be developed for a potentially efficacious clinical application for AD.