To analyze mechanical behavior of Q460 highstrength singleangle steel struts with an eccentric load at one end in transmission towers, experimental analysis and theoretical calculation were carried out to study the overall stability and local buckling of members. Spherical hinge bearing and double knifeedge bearing were applied at axial end of specimens. Influence of some factors on bearing capacity of compression members with eccentricities at both ends was analyzed, such as the end supporting conditions and residual stresses. It was shown that whether spherical hinge bearing or double knifeedge bearing was used at axial end, the mechanical behavior can be accurately presented and the residual stresses affected the ultimate loadcarrying capacity by about 5％ or less. Compared with different methods, such as experiment method、finite element method, method in the Guide for American Design of Latticed Steel Transmission Structure（ASCE101997）and method in Chinese Technical Regulation of Design for Tower and Pole Structure of Overhead Transmission Line (DL/T51542002), it was found that the calculated strength of highstrength steel member by standard calculation method in DL/T51542000 was overconservative. According to the research results, the revised formulas of ASCE were proposed with dividing actual material strength by the resistance coefficient of rR=1.111. Therefore, the experimental results can provide reference for designing highstrength Q460 singleangle steel members compressed eccentrically at one end.