Objective To investigate the effect of facet joint asymmetry on lumbar biomechanics in normal and patients with adolescent lumbar disc herniation (ALDH).   Methods Mimics 21.0, 3-Matic Medical 13.0, Geomagic Wrap 2017, HyperMesh 2019 and finite element software ABAQUS 2021 were combined to establish three-dimensional finite element models of normal lower lumbar spine and adolescent lumbar disc herniation. According to the difference between the left and right facet joints, three cases of normal and ALDH  patients aged 13-18 years old were selected, with a total of 6 cases. The stress of intervertebral disc under different torque loads (neutral position, lateral flexion and rotation) was analyzed and compared.   Results 1. Three dimensional finite element models of L3-L5 segments were established in 6 male normal and adolescent patients with lumbar disc herniation, and the stress and displacement nephogram of lumbar disc herniation in normal neutral position, flexion, extension, lateral flexion and rotation were obtained; 2. The stress of L4-5 annulus fibrosus increased when the facet joint angle of normal adolescents was symmetrical in the neutral position; 3. The stress of annulus fibrosus was greater than that of nucleus pulposus under different conditions, and the stress of annulus fibrosus was flexion > neutral position > extension; 4. In patients with ALDH, the left side of the facet joint was larger than the right 10 ° model, and the stress in the posterior side of the annulus fibrosus of L4-5 segment increased significantly under extension condition. Under lateral flexion condition, the left stress of the left annulus fibrosus was compared with the right stress of the right annulus f  ibrosus, t=1.575, P<0.05, the difference was statistically significant, the right stress of the right annulus fibrosus was greater than the left stress of the left annulus fibrosus. Under the rotating condition, the stress on the left and right sides of the fiber ring was greater than that on the back side.   Conclusion 1. Compared with normal and patients with ALDH, the stress of intervertebral disc increases under different postures, which may increase the shear load of intervertebral disc and aggravate the process of intervertebral disc degeneration; 2. When the degree of left-right asymmetry of facet joint is more than 10 degrees, the stress on the side with small degree is greater. Facet joint asymmetry can lead to the overload of vertebral body and intervertebral disc, leading to spinal instability; 3. The stress of intervertebral disc in extension is less than that in neutral position and flexion. Extension can relieve the pressure of intervertebral disc and play an auxiliary role in the recovery of patients with ALDH.