To describe a grading system that can be used to evaluate core competency of clinical nurse specialists (CNSs) at different levels. Evaluate core competence of CNSs at different levels reflects the quality of nursing and the development of the nursing profession. This research employed the Delphi method. The STROBE checklist for observational cross-sectional studies was followed to report this research study. This study consisted of two main phases: a literature review and semistructured interviews. Individual semistructured interviews were conducted with 11 healthcare experts and two patients. Two rounds of questionnaire surveys were administered to 21 nursing experts using the Delphi method. The CNSs were classified as primary, intermediate or advanced based on their years of work, professional titles and educational qualifications. The graded competency evaluation system consisted of five first-level indicators (clinical practice, consulting guidance and teaching, scientific research innovation, management and discipline development, and ethical decision-making), 15 second level indicators, and 40 third-level indicators. The authority coefficients (Cr) of the experts were .865 and .901. The Kendall's concordance coefficients of the three-level indicators were .417, .289 and .316 for primary CNSs; .384, .294 and .337 for intermediate CNSs; and .489, .289 and .239 for advanced CNSs. The graded use evaluation system in clinical practice initially involves a comprehensive evaluation of the core abilities of CNSs. This is a tool for cultivating and grading the abilities of specialised nurses that can promote a practical upwards spiral. The evaluation system can promote the scientific management and continuous improvement of CNSs in clinical nursing and can serve as a practical and objective reference for the effective management and development of CNSs. Patients participated in the data collection process, during which they shared their health-seeking experience with our research team.