Left hip is also known as the left hip joint, left hip joint pain may be caused by obesity, sports load and other physiological reasons and hip osteoarthritis, femoral head necrosis and other pathological reasons. 1. Physiological reasons: the hip joint is an important load-bearing joint in the human body, obese people due to gravity conduction, which can lead to increased pressure on the hip joint, long-term wear and tear leading to the emergence of pain symptoms; sports load of the population, due to the hip joint and the surrounding soft tissues of the prolonged fatigue injuries, the above symptoms may also occur. 2. Pathological reasons: when osteoarthritis occurs in the hip joint due to various reasons, degeneration of hip joint cartilage and aging of joints will occur, and soreness of the hip joint may also occur, such as rheumatic hip arthritis, ankylosing spondylitis, etc. When trophoblastic vasculopathy of the femoral head occurs due to various reasons, and necrosis of the femoral head occurs, the above mentioned symptoms will also occur. The symptoms of left hip soreness alone sometimes can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results to make an accurate judgment, it is recommended to clarify the cause of the disease under the guidance of a doctor.