The invention relates to a method for promoting the shearing performance of a carbon/carbon-lithium aluminum silicon joint. The method comprises the following steps: firstly, constructing a honeycomb porous structure on a surface of a modified layer of a silicon base ceramic by utilizing a controllable oxidizing method, and then forming an interlocked embedded interface structure by a glass interlayer and the modified layer in a hot-pressing process. According to the invention, through the design of the embedded interface structure, the effective connecting area of the modified layer and the glass interlayer is obviously increased, and the problem of weak binding of the interface is solved to a certain extent. The average shearing strength of a C/C-LAS joint prepared according to the method can reach up to 32.46+/-1.35MPa and is 35% higher than that of a gradient joint of the patent 1. Through the construction of the embedded interface structure, the effective connecting area of the modified layer and the interlayer is increased, the problem of weak binding of the interface is solved to a certain extent, and the shearing strength of the C/C-LAS joint is obviously increased.