<p>As the field of in-situ stress testing technology moves towards complex ultra-deep strata, it poses new challenges to the stability and pressure-bearing performance of key down-hole exploration tools. Because the packer in the deep setting is frequently subjected to severe alternating load impacts and its material is prone to creep and aging under the synergistic effect of high temperature and high pressure, the risk of fatigue failure of the sealing element is doubled. To this end, we carried out the mechanical properties test of the main sealing steel strip, and systematically analyzed the influence of the steel strip skeleton structure, thickness, stacking parameters and material properties on the sealing performance and pressure bearing capacity of the packer, which filled the gap of the slip and stress mutation of the traditional steel strip packer in the three-dimensional expansion. The results show that: (1) With the increase of internal pressure, the contact pressure is positively correlated with the internal pressure, and the structural stress and shear stress level of the rubber tube and steel strip at the shoulder are the highest. (2) By improving the shoulder structure of the packer, the extreme value of rubber stress is reduced by 73.6 %, thus prolonging the service life of rubber. (3) The analysis shows that the thinning of the steel strip and the steel strip layer will bring about instability, and the thickness of the steel strip is 1 mm, and the stacking thickness is 10 mm, which can take into account the sealing length and safety factor of more than 87 %. (4) By comparing three steel strip materials with different strengths and optimizing their setting effects, the use of 17-4PH material can increase the structural safety factor by 36.36 %.</p>