Objective To develop a Scale for Clinical Nursing Preceptors′ Competence in Evaluating Nursing Students′ Clinical Practice Performance, and to provide a basis for implementing targeted interventions. Methods Based on the "Conceptual, Praxeological, and Socio-emotional （CPS）" three-dimensional framework of teachers′ evaluation competence, the scale was developed through literature review, focus-group discussion, two-round Delphi consultation, and a pilot survey.Convenience sampling was used to recruit 520 clinical nursing preceptors between December 2024 and April 2025 to examine the scale′s psychometric properties. Results The final scale comprised 3 dimensions and 34 items.Exploratory factor analysis results indicated that the cumulative variance contribution rate of the three common factors was 75.161%.Confirmatory factor analysis (CFA) indicated a good model fit (χ2/df=1.315, RMSEA=0.034; GFI, AGFI, RFI, NFI, CFI, IFI and TLI all ＞0.900).The scale-level content validity index (S-CVI) was 0.882, and the item-level content validity index (I-CVI) ranged from 0.917 to 1.000. The Cronbach′s α coefficient, split-half reliability and test-retest reliability of the total scale were 0.922, 0.925 and 0.928, respectively. Conclusion The Scale for Clinical Nursing Preceptors′ Competence in Evaluating Nursing Students′ Clinical Practice Performance has good reliability and validity, and can be used as an effective tool to assess the competence level of clinical nursing preceptors in China in evaluating nursing students′ clinical practice performance.