Abstract: This study investigated the interfacial mechanical properties of unidirectional C/SiC ceramic matrix composites using micro-nano mechanical testing techniques. An improved single-fiber push-out test was developed to quantitatively assess the interfacial fracture toughness from an energy perspective. The results showed that the interfacial debonding shear strength (IDSS), frictional shear strength (IFSS), and fracture toughness (IFT) were 35.2±5.1 MPa, 10.1±1.0 MPa, and 22.5±2.8 J/m², respectively. The proposed method effectively characterized the interfacial properties without relying on assumptions regarding stress distribution or friction. During the fiber push-out process, failure primarily occurred at the fiber-matrix interface, with energy dissipation mainly due to interfacial debonding and friction. The specimen thickness (50-100 μm) was found to be optimal, and the load-displacement curve revealed the initiation and propagation of interfacial cracks.