Frozen shoulder is diagnosed by physical examination, X-ray and magnetic resonance examination. The details are as follows: 1. Physical examination: the patient has severe shoulder pain, limited shoulder movement, and the arm cannot be lifted or even posteriorly extended; 2. X-ray: it is not directly helpful for the diagnosis of frozen shoulder, but it can be used as a routine diagnostic procedure to rule out whether there may be lesions of the shoulder joint bone tissue itself, such as tendon calcification, hooked acromion or acromion osteophytes; 3. MRI: it clearly shows the shoulder joint surrounding ligament, cartilage, joint lip and other structural signals, and extensive inflammatory manifestations.