Objective To evaluate the diagnostic value of ultrasound in frozen shoulders by evaluating the ultrasound findings of shoulder and joint capsule thickness in asymptomatic healthy people and frozen shoulder patients.Methods Thirtyfour patients from Aug 2018 to Oct 2018 with frozen shoulders were enrolled in our study. In the same period, 53 patients without any shoulder joint symptoms were used as the control group. Ultrasound examination of the shoulder joint was performed to analyze the thickness of the joint capsule. The ultrasound performance of the shoulder joints and the thickness of the joint capsule were compared. Results The mean thickness of the male in the control group was greater than that of the female, which was statistically significant (P＜0.01). There was no difference in the thickness of the joint capsule between the left shoulder and the right shoulder of the male and female. The thickness of theunderarm joint capsule was positively correlated with height (r=0.323) and body weight (r=0.317), independent of BMI (r=0.163) and age (r=〖CD*3/5〗0.102). Compared with the healthy control group, the underarm joint capsule of the frozen shoulder was significantly thicker, and the difference was statistically significant （P＜0.05）. Conclusion Ultrasound can accurately evaluate the thickness of the joint capsule, the echo of the rotator cuff and the blood flow signal, reflecting changes in the morphology and structure of the patient's shoulder joint, and can be used as an important tool for the diagnosis of frozen shoulder.