The stress concentration factors of concrete-filled tubular Y-joints subject to in-plane bending were studied，based on the engineering background of the first 750 kV concrete filled tubular substation in China.Experimental investigation was performed to investigate the hot spot stress distribution along the intersection between chord and brace.Three tubular Y-joint specimens with circular concrete-filled chords under different forms of reinforced components，including doubler-plate，sleeved and haunched reinforced joints，were tested.In addition，a unreinforced joint specimen was tested for comparison.The test results indicate that three different forms of reinforced components effectively reduce the peak stress concentration factors of Y-joints，compared with that of the unreinforced joint.The current research points out that the linear extrapolation method can be used for chords，whereas the quadratic extrapolation method can be used for braces.The stress concentration factor values are effectively reduced and more evenly distributed when the axial compression ratio in chord is increased.Furthermore，the stress concentration factors obtained from the test results were compared with the predictions from some well-established existing stress concentration factor equations.Generally，the prediction results are very consistent with the test results of the braces，but very conservative for concrete-filled chords.