Purpose: This study was to develop the clinical competency evaluation, and to examine the effects of the developed evaluation by comparing it with existing evaluation on clinical competency, communication skill, and self-efficacy of nursing students. Methods: Design was a randomized control group post-test design. The subjects were 102 senior nursing students(Experimental group: 48, Control group: 54) at K university in seoul, Korea. The experimental group took the clinical competency evaluation using standardized patients and the control group took the existing evaluation using a doll. The clinical competency and communication skills were measured by evaluators, and self-efficacy was self reported by the nursing students. Results: The experimental group had higher scores in clinical competency, communication skills, and self-efficacy than those in the control group. Conclusion: Through these results, practice education of nursing education programs need to activate the clinical competency evaluation using standardized patients.