To obtain the cubical coefficients of thermal expansion of a mixed system of flaky dust and alkane liquid, the volume and pressure of the mixed system under different temperatures and volume fractions of aluminum powder were measured. On the basis of the experimental results, the cubical coefficients of thermal expansion under the corresponding conditions were calculated and the effect of each influencing factor was obtained. The results show that since the volume of each phase component in the system increases with temperature, the volume of the mixed system also increases with temperature. With increasing temperature, the cubical coefficients of thermal expansion of the mixed system generally increase. Affected by the increase in mass concentration of low-expansion-coefficient substances, an increase in the volume fraction of aluminum powder results in a decrease in the volume thermal expansion coefficient of the mixed system. At the same time, due to the changes in the state of the mixed system, the mass fraction of aluminum powder decreased sharply within a certain range. The low mass fraction of aluminum powder weakens the supporting effect of the metal particle skeleton, the thermal expansion properties of the liquid dominate the mixed system, and the volume thermal expansion coefficient is high. The high aluminum powder mass fraction creates the metal particle skeleton, the metal thermal expansion properties dominate the mixed system, and the volume thermal expansion coefficient is low.