Objective To investigate the relationship between the elbow flexion angle and the cubital tunnel pressure in patients with cubital tunnel syndrome. Methods Between June 2010 and June 2011, 63 patients with cubital tunnel syndrome were treated. There were 47 males and 16 females with an average age of 59 years (range, 31-80 years). The lesion was at left side in 18 cases and at right side in 45 cases. During anterior transposition of ulnar nerve, the cubital tunnel pressure values were measured at full elbow extension, elbow flexion of 30, 60, and 90°, and full elbow flexion with microsensor. The elbow flexion angle-cubital tunnel pressure curve was drawn. Results The cubital tunnel pressure increased smoothly with increased elbow flexion angle when the elbow flexed less than 60°, and the pressure increased sharply when the elbow flexed more than 90°. The cubital tunnel pressure values were (0.13 ± 0.15), (1.75 ± 0.30), (2.62 ± 0.34), (5.78 ± 0.47), and (11.40 ± 0.62) kPa, respectively at full elbow extension, elbow flexion of 30, 60, and 90°, and full elbow flexion, showing significant differences among different angles (P lt; 0.05). Conclusion The cubital tunnel pressure will increase sharply when the elbow flexes more than 90°, which leads to the chronic ischemic damage to ulnar nerve. Long-term ischemic damage will induce cubital tunnel syndrome.