Objective To develop the Clinical Situational Awareness Scale for ICU Nurses and verify its reliability and validity, so as to provide a valid assessment tool. Methods Based on Endsley′s Three-level Model, initial items were formulated by literature review, interviews and expert consultation.A total of 594 ICU nurses were enrolled for questionnaire survey and psychometric testing. Results The scale contained 4 dimensions and 38 items:basic sensory ability, cognitive-emotional comprehensive ability, information collection and integration ability, and information processing ability.The cumulative variance contribution rate of exploratory factor analysis was 66.982%.Confirmatory factor analysis showed acceptable model fit:χ2/df=2.471, RMR=0.026, RMSEA=0.074, IFI=0.881, CFI=0.881, TLI=0.872. The S-CVI was 0.984, I-CVI ranged from 0.903 to 1.000.The overall Cronbach′s α was 0.975, and split-half reliability was 0.943. Conclusion The scale has good reliability and validity, which is sui-table for evaluating clinical situational awareness of ICU nurses, and can provide evidence for nursing management and training.