Pain in the back of the thigh may be localized muscle pain, or it may be pear-shaped muscle syndrome or sciatica. Generally, localized muscle pain is due to long-term chronic strain, or incorrect exercise strains that cause pain. There are three main muscles on the back of the thigh, the biceps femoris, semitendinosus and semimembranosus, and injuries to them generally cause pain. In pear-shaped muscle syndrome, damage to the pear-shaped muscle is due to excessive spasm and tension of the pear-shaped muscle. After injury to the pear muscle, local congestion and edema or spasm leads to hypertrophy of the pear muscle, resulting in narrowing of the pear foramen, which can directly compress the sciatic nerve and result in pear muscle syndrome. This can produce pain in the posterior hip and posterior thigh. In addition, lumbar disc herniation can also produce posterior thigh muscle pain symptoms, and when the lumbar disc herniation is severe and compresses the nerve root, pain symptoms in the innervated area can occur. Therefore, the causes of pain in the posterior thigh are diverse and need to be confirmed with specific clinical investigations and imaging examinations.