BNi-2 braze was used to brazing C/C composite panel and GH3536 superalloy honeycomb under the brazing parameter at brazing temperature of 1040 ℃ and holding time 15 min. The influence of the thickness of brazing braze on the microstructure and flatwise tensile strength of C/C composite and superalloy honeycomb sandwich structure was analyzed. Results show that the panel-honeycomb interface can be divided into reaction zone between C/C composite and braze, reaction zone between braze and honeycomb and braze solidification zone. Cr₃C₂ reaction layer is formed between braze and C/C composite. Intermetallic compounds of Si are formed within the reaction zone between braze and honeycomb. With the increase of thickness braze, flatwise tensile strength increases first and then decreases. When the braze thickness is 0.12 mm, flatwise tensile strength reaches the maximum level at 9.69 MPa. The fracture site mainly occurs in the C/C composite base material.