The pain on the upper side of the left testicle may be caused by testicular inflammation, varicocele, trauma and other diseases such as testicular torsion. 1. Orchitis: the causes of orchitis are mostly related to bacterial, chlamydial, mycoplasma and viral infections, with clinical manifestations such as high fever, testicular enlargement, pain and other symptoms, and inflammation mostly occurs unilaterally. If the patient suffers from orchitis, there may be pain on the upper side of the left testicle. 2. Varicocele: The etiology of varicocele is not clear yet, and it may be related to venous valve insufficiency, venous return obstacle and other factors. Varicocele is more common on the left side, and the patient may have enlarged scrotum, accompanied by a feeling of swelling, hidden pain and other symptoms. 3. Trauma: If the patient’s left testicle suffers from extrusion and collision of external substances, it may lead to localized injury, which may lead to symptoms of pain in the left testicle. 4. Other diseases: testicular torsion, tuberculosis and tumors can also cause pain in the upper side of the left testicle. There are many causes of left testicular pain, we suggest that patients go to regular hospitals to consult doctors and cooperate with them to conduct relevant examinations to clarify the causes.