In recent years, organic-inorganic hybrid perovskite materials have been widely used in solar cells, photodetectors, and light-emitting diodes due to their advantages such as high light absorption coefficient, good carrier mobility, and long carrier diffusion length. However, the high toxicity of lead and poor stability still restrict the application and promotion of such materials. The lead-free double perovskite material derived from the concept of “heterovalent substitution”, while maintaining the high symmetrical structure of perovskite, avoids using the toxic lead elements, which has the advantages of environmental friendly, stable structure, and suitable band gap. At present, the limited research on lead-free double perovskite materials still leaves a big room to researchers, and such a limited research seriously restricts the development and promotion of such materials. Therefore, the relationship between the structure and performance of lead-free double perovskite materials needs further exploring in order to provide theoretical basis for the practical application of such materials. Here in this work, the lead-free double perovskite material Cs ₂TeCl ₆is prepared by the solution method. The crystal structure and optical properties of the lead-free double perovskite Cs ₂TeCl ₆under high pressure are investigated by using diamond anvil cell combined with in-situhigh-pressure angle-dispersive X-ray diffraction and ultraviolet-visible absorption technology. The results show that the crystal structure of Cs ₂TeCl ₆is not changed within the experimental pressure range of 0－50.0 GPa, and the structural symmetry of Fm-3 mis still maintained, indicating the sample has good stability. The lattice constant and volume of Cs ₂TeCl ₆gradually decrease within the pressure range of 0－50.0 GPa. The volume and pressure of Cs ₂TeCl ₆are fitted using the third-order Birch-Mumaghan equation of state, the bulk elastic modulus is obtained to be B ₀= (18.77 ± 2.88) GPa. The smaller bulk elastic modulus indicates that the lead-free double perovskite material Cs ₂TeCl ₆has higher compressibility. The optical band gap of Cs ₂TeCl ₆is 2.68(3) eV at 1 atm and its optical band gap gradually decreases with the increase of pressure, which is related to the shrinkage of octahedral [TeCl ₆] ^2–under high pressure. The calculation results show that the Cs ₂TeCl ₆possesses an indirect band gap, the valence band maximum is mainly composed of Cl 3p orbits, and the conduction band minimum is mainly composed of Te 5p and Cl 3p orbits. After the pressure is completely relieved, Cs ₂TeCl ₆returns to the initial state. The above conclusions further deepen the understanding of the crystal structure and optical properties of lead-free double perovskite Cs ₂TeCl ₆, and provide a theoretical basis for designing and optimizing the lead-free double perovskite materials.