Abstract: The moment of inertia of fillet welds is an important factor for calculation of strength of welds when the tubular joint is subjected to in-plane bending． This paper conducts the analysis of weld profile such as the effective area and the moment of inertia． The numerical method adopts the effective section presumption for welds and takes the consideration of dihedral angle，which is the angle between the chord and the brace surfaces along the intersection line，to evaluate the weld profile． Based on the finite element analysis，the approach formula for moment of inertia and the strength calculation of fillet welds for tubular joints under in-plane bending are proposed． The comparison of the results by the approach formula and finite element analysis indicates the safety of the bending strength calculation of fillet welds by the method based on the analysis of weld profile．