To research the mechanical behavior of circular concrete filled steel tubular (CFST) truss, four truss specimens of the different sections such as rectangular truss, inverse-triangular truss, trapezoid truss and triangular truss were tested under static point loading. Results of these tests showed that truss specimens are stressed more in the segment 0 - 2/6l of the bottom chord, expect specimen TT which is stressed more in the top chord. The difference among these trusses sections has a great influence on the axial force of chord, and each segment bears quite large in-plane bending moment, but it has different influence on the web members. Among these trusses,webs of specimen IT have a more reasonable condition. The influence on web in-plane bending moment is larger and larger as the following order: rectangular section, trapezoid section, inverted triangularsection, furthermore, force condition of bottom chords is more and more complex. To the top chords filled concrete, section "weaken" from rectangular section to trapezoid section, inverted triangular section, and triangular section makes a different influence on in-plane bending moment of each segment.%对矩形断面、倒三角形断面、梯形断面和正三角形断面4榀圆钢管混凝土桁架进行对比试验,研究不同断面形式的桁架受力分布模式.结果表明,桁架试件在0-2/6l段的桁架下弦节点受力较大,而试件Tr上弦节点受力较大；断面形式的不同对桁架的上、下弦杆的轴力影响较大,且弦杆各个节段均承受很大的平面弯矩,而对腹杆的轴力分布模式影响不同,其中试件IT的腹杆受力比较合理.断面从矩形、梯形到倒三角形,对腹杆平面内弯矩影响越来越大,且下弦杆受力情况也越来越复杂；填充混凝土的上弦杆从矩形、梯形到倒三角形、正三角形这种断面的“削弱”对各段的杆件平面内弯矩影响不同.
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