PURPOSE: The Purpose of this study was to investigate the changes in the thickness of Sternocleidomastoid muscle(SCM) and deep cervical flexor muscle(DCF) through CranioCervical Flexion Exercise(CCFEx) Using Sling. METHODS: Subjects were randomly allocated two group: control group (n=21) without neck pain, experimental group (n=17) with pain. Muscle thickness was measured using CranioCervical Flexion Test(CCFT) and ultrasonography before or after intervention. RESULTS: In experimental group, compared with muscle thickness of exercise before, SCM thickness rate of change was slightly decreased according to pressure increased after exercise(p<.05). CONCLUSION: The results of this study showed that CCFEx using sling is effective for SCM and DCF of choric neck pain patients.