Frozen soil is a composite material composed of soil particles, ice, unfrozen water, and gas, and with unstable mechanical properties. The amount of ice determines its temperature sensitivity, and previous research has shown that its negative temperature is the most critical factor that determines its strength; therefore, temperature is a key factor in regulating the bearing capacity of a frozen soil foundation. As the main foundation of major constructions in unstable and ice-rich permafrost regions, a pile foundation is widely used because of its relative stability during permafrost degradation. The freezing strength of a soil-structure interface in the cold regions can be viewed as a complicated functional form of the soil property, temperature, water content, interface roughness, and normal pressure, which directly influence the bearing capacity and stability of the upper structure. Series of laboratory direct shear tests of the interface between the Qingzang Clay and a steel plate of different roughness were performed. Based on the direct shear tests and an orthogonal design method, the influence factors, influence degree, and mechanical behavior of the shear strength of soil-structure interface were studied. The results show that the amount of water content in the interface has the greatest influence on its shear strength. From laboratory tests, the maximum and minimum interfacial shear strength is 0.45 MPa and 0.13 MPa, respectively, under the different test conditions. Moreover, the shear strength of interface decrease with increasing water content and temperature, and the shear strength increase with increase in the interface roughness and normal pressure. Based on the experimental results, the shear strength of interface can be determined based on Mohr-Coulomb strength criterion; the cohesive strength and internal friction angle are presented in this paper. The results of this study can help prevent and control the disasters of pile foundations at permafrost regions; thus it is of great scientific importance.