Abstract: The brazed joints of metal honeycomb are hard to control due to the difficulties in the inspection and quantitatively evaluation of the joining quality. The nondestructive evaluation on brazed joints of metal honeycombs was studied by means of ultrasonic C scan method. A model was established to describe the structure of the joints, and the effective beam diameter was recognized as the key parameter to the inspection. Experiments were performed and results showed that the beam diameter less than 0.7 honeycomb diameter will lead to C scan image required for quantitatively evaluation of the joining quality, and that the frequency and scanning index can affect the final image to some extent. Software was developed to process the images and evaluate the bonding rate through C scan images of the brazed joints of metal honeycomb.