A method was proposed to realize SiC-SiC bonding at the temperature below 300 ℃. Cu and Au were taken as intermediate layer, and Pt was used to catalyze formic acid atmosphere to pretreat metal surface and provide reducing protective atmosphere for bonding. Firstly, the bonding of SiC samples with Cu layer in N₂ atmosphere, formic acid atmosphere, and Pt catalyzed formic acid atmosphere was studied. By comparing the bonding strength, the possibility of SiC-SiC bonding with Cu interlayer in Pt catalyzed formic acid atmosphere was verified. Secondly, the samples were characterized by scanning acoustic microscope (SAM) and scanning electron microscope (SEM). The influence of key process parameters on the bonding strength was studied by changing the bonding temperature and pressure. Finally, the SiC-SiC bonding results of Cu and Au in different atmospheres were compared. Results show that compared with N₂ atmosphere and formic acid atmosphere without Pt catalysis, Pt catalyzed formic acid atmosphere reduced the oxides on the surface of Cu effectively and realized SiC-SiC bonding with Cu interlayer at low temperature. SAM and SEM images show that there was no obvious void in the bonding interface. Compared with SiC samples with Au interlayer, the bonding strength of SiC samples with Cu interlayer was significantly higher at low temperature, which indicates the superiority of the proposed method in the metal surfaces with oxidation layer. High-strength SiC-SiC bonding at low temperature was achieved through Pt catalyzed formic acid atmosphere pretreatment and protection. Shear strength of 12.5 MPa at 200 ℃ was obtained, and an effective bonding between SiC and SiC was achieved.