Objective To study the fall risk of older adults stepping over obstacles of different heights with their dominant or non-dominant legs and provide references for developing fall prevention measures for the elderly during obstacle-crossing. Methods Sixteen older adults randomly stepped over obstacles at 15%, 30%, and 45% of their leg heights with their dominant and non-dominant legs. A three-dimensional (3D) motion capture system and 3D force platform were used to record kinematic and kinetic data. Results When older adults used their non-dominant leg to step over obstacles, the dynamic stability in the anterior-posterior direction of the trailing leg at 30% of leg length height was significantly lower than that at 15% of leg length height (P < 0.05, Cohen’s d = 0.628); the vertical toe clearance of the trailing leg was significantly smaller than that of the dominant leg (P = 0.041, Cohen's d = 0.516), and the vertical toe clearance (P<0.001, Cohen's d = 0.685) and anterior-posterior toe clearance (P = 0.043, Cohen's d = 0.616) of the leading leg were significantly greater than those of the dominant leg. Conclusions Compared to stepping over obstacles with the dominant leg, older adults have a greater risk of falling in the anterior-posterior direction before obstacles when using the non-dominant leg. There is also a greater risk of the trailing leg tripping over obstacles of different heights.