The pain at the root of the left thigh and hip joint when walking may be caused by femoral head necrosis, hip synovitis, sacroiliac arthritis, ankylosing spondylitis and other diseases, and may also be caused by tumor-related diseases. It is recommended that patients go to the hospital in a timely manner to get a diagnosis and follow medical advice for treatment.1. Femoral head necrosis: The main cause is the history of hip trauma or long-term alcohol consumption, causing femoral head necrosis and collapse, which can cause pain at the root of the left thigh and hip joint, radiating to the ipsilateral hip or knee joint. Magnetic resonance or CT examination can confirm the diagnosis, mild necrosis is recommended for conservative treatment, such as avoiding weight-bearing on the hip, in serious cases, artificial arthroplasty treatment is needed; 2, hip synovitis: infection, immunity, trauma and other causes of hip synovial hyperplasia combined with inflammatory reaction, resulting in pain in the pelvis and thigh joint, can appear walking left leg thigh root and hip joint pain, magnetic resonance, etc. The diagnosis can be confirmed after relevant examinations, and the patient can generally apply Celecoxib capsules, indomethacin tablets, synovitis tablets and other drugs as prescribed by the doctor to relieve the symptoms, and should also pay attention to proper rest; 3, sacroiliac arthritis: when the sacroiliac joint has a sterile inflammatory reaction, the joint space is blurred and narrowed, and the pain can radiate from the sacroiliac joint to the root of the thigh, and the patient can follow the doctor’s prescription for pain at the root of the thigh and crotch joint of the left leg when walking. Application of diclofenac sodium extended-release tablets, celecoxib capsules and other drugs to relieve pain; 4, ankylosing spondylitis: genetic, immune, infectious and other causes of inflammatory reaction of the sacroiliac joint of the spine, resulting in vague pain at the root of the thigh and across the joint, can appear walking left leg thigh root and crotch pain, patients can take celecoxib capsules, naproxen tablets and other drugs for pain management as prescribed by the doctor; 5, tumors. Such as femoral neck bone cyst, pelvic tumor, etc., tumor tissue can stimulate the surrounding nerve tissue, resulting in thigh pain and discomfort and pain at the root of the left thigh and crotch connection when walking. Patients need to first puncture for pathological examination to confirm the nature of the diagnosis, and then decide to take surgery, chemotherapy and other treatments according to the examination report.