This paper aims to explore the brittle fracture characteristics and fluctuation behavior of cutting force during scratch process of RB-SiC with different scratch depth and indenter shapes. The diamond Berkvoich indenter with 400 nm and conical indenter with 8.7 um were used to conduct experiments under constant scratch depth mode. Then, the surface morphologies and brittle fracture behavior were observed with a scan electron microscopy (SEM). Finally, Daubechies wavelet was adopted to decompose the lateral and tangential forces, and the relationship between different detail signal/decompose signal and damage types were given. The results show that with the increasing of scratch depth, plastic extrusion, micro fracture and large area fracture are coexist when conical indenter is used. Besides, the degree of fracture is more serious and cutting force signal energy spread from low-frequency to the whole frequency with the decrease of indenter radius and the energy of low-frequency band energy gradually occupied the dominates position. Surface and margin microfracture make the dominate contribution to the detail signal of cutting force. Scratching force fluctuation energy is mainly come from the structure difference and defects of RB-SiC which caused mass crushing, and increased with scratch depth.