Abstract: Ceramic-to-metal packaging is widely used as a key process in electronic vacuum devices in integrated circuit packaging, medical devices, and defence.The flatness of the two connections determines the reliability of the chip, and it is of great significance for the development of the semiconductor industry to predict and control the change of ceramic flatness after encapsulation.Design of experiments for ceramic-metal brazing based on a high-temperature co-fired ceramic-metal structure using the response surface method to simultaneously investigate the effects of multiple experimental variables on the flatness of ceramic-metal brazing.The change in ceramic flatness before and after brazing was taken as the response value, and a prediction model with quadratic polynomial regression equations was developed using a CCD combinatorial design to investigate the effect of ceramic size and metal size on the change in flatness.The results show that increasing the height of the ceramic or decreasing the length of the ceramic sides and the thickness of the wall reduces the change in flatness.At the same time, the ceramic size has a more significant effect on flatness, while the wall thickness plays a smaller role in affecting flatness. The results provide a reference for the prediction and control of ceramic brazing flatness.