This paper numerically studied the compression behaviours of ultra-high performance concrete - filled square high strength steel tubes (UFSHTs) at low temperatures. Firstly, finite element models (FEMs) were developed to simulate the ultimate strength behaviours of UFSHTs under bending and compression, which were extensively validated by bending and compression test results. Then, extensive FEM analysis were carried out to investigate the low-temperature eccentric-compression behaviours of UFSHTs at low temperatures. The studied parameters in this numerical analysis included low temperatures, eccentricities, and slenderness ratios. The FEM parametric studies showed that (1) reducing low temperatures improved the eccentric-compression capacities; (2) The load-displacement curves exhibited a more protracted hardening stage with higher eccentricity ratios; (3) the normalized N-M curves were shrunk inward with slenderness ratios increasing. Finally, modified code equations were proposed to estimate the N-M interactions of UFSHTs under low-temperature eccentric-compressions, and validations of the predictions against the test and numerical results confirmed that the modified Eurocode 4 code equations provided more reasonable estimations than AISC360 and GB50936.