Abstract: In order to analyze the characteristics of steel tubefrozen soil composite structure in bending process, based on the research results of laboratory test, the variation law of bearing capacity of steel tubefrozen soil composite structure is analyzed with ANSYS software. The conclusions obtained in the study are as follows:（1）The ultimate bearing capacity of steel tubefrozen soil composite structure can be increased by 52.6% when steel tube is arranged at the bottom of frozen soil structure；the stress distribution on composite structure section under load shows "stratification" phenomenon, and the stress calculation process satisfies the assumption of beam flat section. (2)When the shear stress between the steel tube and frozen soil exceeds its shear strength, the steel tube and frozen soil will slip, but the independent bearing capacity of the steel tube and frozen soil can still exert the bearing capacity of the composite structure. （3）The increase of the steel tube diameter and wall thickness can improve the ultimate bearing capacity of the composite structure；the ultimate bearing capacity of the steel tube arranged at the bottom of the structural section can obviously improve the bearing capacity of the composite structure, and its ultimate bearing capacity is about 30% higher than that of the steel tube located at the center or top of the section.

Key words: artificial freezing, steel tubefrozen soil composite structure, bending mechanical properties, numerical simulation; ultimate bearing capacity