There are many reasons for pain on both sides of the thigh, such as lactic acid accumulation, trauma, ankylosing spondylitis, high lumbar disc herniation, femoral head necrosis and femoral neck tumor. 1. Lactic acid accumulation: long-distance running, long-distance walking, squatting, etc. will lead to accumulation of local lactic acid, which cannot be metabolized out of the body in time, thus causing pain on both sides of the thigh. 2. Traumatic injury: a history of traumatic injury to the thighs will also cause pain on both sides of the thighs, accompanied by limited mobility, localized bruising and other phenomena, and even cause fractures. 3. Ankylosing spondylitis: early ankylosing spondylitis will have inflammatory pain, with the gradual development of the disease, it will also cause hip joint activity limitation, deformity, which will lead to pain on both sides of the thigh. 4. High lumbar disc herniation: High lumbar disc herniation can cause femoral neuralgia and lateral femoral cutaneous neuralgia, which will lead to pain on both sides of the thighs, accompanied by sciatica. 5. Necrosis of the femoral head: when there is aseptic necrosis of the femoral head, because the femoral head stimulates the joint capsule of the hip joint, it will cause pain on both sides of the thigh. 6. Tumor of femoral head: when tumor of femoral head occurs, because the tumor tissue invades the muscles and soft tissues on both sides of the thigh, the clinical symptoms of pain on both sides of the thigh will appear. There are many reasons leading to pain on both sides of the thigh, if the symptoms can not be relieved for a long time, it is recommended that the patients go to the hospital in time to improve the examination and take standardized treatment according to the doctor’s instructions, so that they can not delay the condition and the treatment of the condition.