Abstract: Objective: To investigate the present situation of professional identity among Clinical Nursing Specialists (CNS) from tertiary hospitals in Haikou, and analyze the influencing factors. Methods: The Nurse Professional Identity Scale (NPIS, Chinese version) was used to investigate all 198 CNS from tertiary grade A hospitals in Haikou. Results: Their NPIS was 5.70±0.62, the descending order of standardized score in the 7 dimensions was self determination, the sense of organization, the sense of meaning, the sense of self efficacy, the sense of patient influence, the sense of feeling holding, the sense of coherence. The average scores of NPIS in different fields were 5.23-6.20, the descending order of standardized score in the different fields was stoma care, critical care, PICC, operation room nursing, blood purification nursing, oncology nursing, emergency nursing, and nutrition nursing. There are significant differences among nurses from different fields in the scores of general NPIS and several dimensions, including feeling holding, the sense of coherence, and the sense of meaning. Professional positions, gender, post allowance, specialist in the ICU field, continuing education, participating in academic meetings, publishing papers entered the regression equation, the combined interpretation 35.8% of the total variation. Conclusion: The NPIS of Clinical Nursing Specialist from tertiary grade A hospitals in Haikou is at a high level. The score in self determination dimension is the highest, while that of sense of agreement is the lowest. Professional identities of Clinical Nursing Specialist from different fields are different.