The time it takes for hip synovitis to heal on its own in a 2 year old baby cannot be generalized; it can take about a week for a short period of time or months for a long period of time. Hip synovitis, also known as transient (temporary) synovitis of the hip joint, is a kind of transient synovitis caused by non-specific inflammation, prevalent in children, the self-healing time is affected by the severity of the disease, clinical manifestations and other factors, the general condition of the less severe, often a week to recover, but the seriousness of the disease may take several months. When a 2-year-old baby has hip synovitis, he should go to a regular hospital and be treated under the guidance of a doctor, and avoid excessive abduction, external rotation or internal retraction and internal rotation activities of the baby’s lower limbs in his life.