LTCC packaging substrate has attracted more and more attention in the industry because of its good signal transmission characteristics and conductivity. High-CTE LTCC packaging substrate is widely used in high-density large-scale integrated circuit packaging because of its good thermal matching with PCB, which ensures the reliability of secondary packaging. However, the bending strength of LTCC with high-CTE is about 200MPa, which is only half of that of traditional HTCC. At the same time, the larger CTE also increases the risk of failure with silicon chip. In this paper, the high-density LTCC packaging substrate and the corresponding verification chip are used to complete the packaging, and a series of reliability tests are carried out. The results show that the high-density LTCC packaging substrate has passed the electrical performance test after completing the temperature cycle, mechanical impact and other tests under the specified conditions, which can meet the general reliability requirements of the devices. However, the chip shear and pull-off strength is only about 1/2 of the HTCC substrate packaging structure. Research on the welding strength is an important direction to improve the application effect of LTCC. The conclusion of this paper provides a reference for the application of high-CTE LTCC.