[Objective] The properties of aggregate-cementitious matrix interface in rock-filled concrete (RFC) are key factors influencing its mechanical performance. The unclear evolutionary mechanisms of these interface characteristics restrict the in-depth understanding of the mechanical properties of RFC at early ages. This study aims to systematically clarify the effects of interfacial roughness and curing age on the shear performance and crack evolution laws of the RFC aggregate-cementitious matrix interface, thereby filling the research gap in the mechanical property characterization of early-age RFC interfaces and providing a theoretical basis for the engineering application and performance optimization of RFC. [Methods] Binary specimens consisting of a single rock block and self-compacting concrete (SCC) were prepared with two interfacial roughness levels (d = 2 mm and 5 mm) and cured for 1, 3, 7, 14, and 28 days. 45° inclined shear tests were carried out while digital image correlation (DIC) was employed to capture full-field displacement and strain evolution. Shear stress-displacement curves, energy dissipation, failure modes, crack width, and strain band width were analyzed. [Results] The shear stress, peak displacement, and energy dissipation of rock-SCC binary specimens all increase with curing age, and the shear strength exhibits a two-stage growth pattern: linear followed by exponential. For specimens with different roughness levels, the differences in shear stress between 28 d and 1 d are 7.12 MPa and 9.66 MPa, respectively, and the corresponding differences in energy dissipation are 6.20 J/cm³ and 8.94 J/cm³. Curing age significantly affects the shear strength of the binary specimens. At different curing ages, the failure cross-sections are mainly characterized by interfacial debonding. When the curing age is less than 7 d, SCC adheres extensively to the grooves. With increasing curing age, SCC adhesion decreases substantially, and the failure path of the specimens tends to occur more along the interface, while the damage distribution becomes more concentrated at the crack tip. The crack width of the binary specimens decreases with increasing curing age, whereas the strain band width gradually increases. [Conclusion] Increasing curing age contributes to the improvement of interfacial shear strength and the expansion of strain band range, and restricts the expansion of interfacial cracks. The period of 7-14 d is identified as the critical stage for the rapid development of early-age RFC interfacial performance. In practical engineering, enhanced moist curing should be implemented during this stage to suppress internal microcrack development and maintain structural bearing capacity, and concrete mix design can be optimized to strengthen early-age hydration-induced chemical bonding effect. In addition, proper surface roughness of rock-fill can effectively improve the shear performance and energy dissipation capacity. Future systematic studies are needed to investigate the influence of roughness on the shear performance of RFC.