Abstract: To study the effects of different expansive agents on the properties of composite cement sealing materials, the effects of different proportions of sodium bentonite and aluminum powder on the compressive strength, expansion rate and permeability of the sample were analyzed by experiments. The results showed that: the increase of sodium bentonite ratio significantly reduces the ultimate compressive strength of the sample, and the increase of aluminum powder has no obvious influence on the sample strength; with the increase of the ratio of different expansive agents, the expansion rate of the sample increased by more than three times; there is a good linear relationship between the permeability of the sample and the reciprocal of the mean pressure of the inlet and outlet gas. With the increase of the expansion agent ratio, the permeability of the material decreases first and then increases.