Objective: To explore the self-assembly and gelation properties of synthetic peptides, and their efficacy on hydroxyapatite (HAP) nucleation and in situ remineralisation of initial caries lesions. Methods: Mass spectrometry and reversed-phase high performance liquid chromatography (RPHPLC) were used to confirm the successful synthesis of peptides. Their self-assembly properties and conformation stability were evaluated using circular dichroism (CD) spectroscopy and Fourier-transform infrared spectroscopy (FTIR). Cell Counting Kit-8 (CCK-8; Dojindo, Kumamoto, Japan) was used to evaluate their cytotoxicity. The efficacy of the peptides on HAP nucleation and in situ remineralisation of initial caries lesions was explored using FTIR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction and transverse microradiography analysis. Results: Two kinds of self-assembly β-sheet peptides named ID4 and ID8, respectively, were successfully synthesised with purities greater than 95%. Both were stable under neutral physiological conditions and had low cytotoxicity. ID4 and ID8 showed calcium responsive self-assembly properties and could self-assemble into nanofibres. Compared with ID4, ID8 resulted in the rapid formation of hydrogel with a lower concentration of calcium, and self-assembled ID8 hydrogel induced the formation of flower-like HAP and significantly promoted the remineralisation of initial enamel caries. Conclusion: ID8 could serve as the template to induce HAP nucleation and promote biomimetic remineralisation of initial caries lesions. These results underpin future research on peptide design, and ID8 may be a promising bioactive component for anti-caries applications. Keywords: β-sheet peptide, hydroxyapatite, initial caries lesions, remineralisation, self-assembly