To translate and validate the Nonverbal Pain Assessment Tool. Timely assessment of the pain degree of nonverbal intensive care unit (ICU) patients can provide humanistic care. However, there is a lack of pain assessment tools that can meet the needs of patients who cannot use language in ICUs in China. A cross-sectional survey. We conducted forward-backward translation of the Nonverbal Pain Assessment Tool. A total of 300 critically ill patients in the intensive care unit who could not communicate verbally completed the Chinese version of the Nonverbal Pain Assessment Tool and the Critical Care Pain Observation Tool. Exploratory and confirmatory factor analyses were performed to verify structural validity, and content validity and reliability analyses were also conducted. The Nonverbal Pain Assessment Tool demonstrated high internal consistency (α = 0.901) and interrater reliability (intraclass correlation coefficient = 0.981), with good split-half reliability. Content validity was established through acceptable item-level content validity index and scale-level content validity index scores. Exploratory factor analysis showed a single factor explaining 71.79% of total variance, and confirmatory factor analysis confirmed good model fit. The Spearman rank correlation coefficient was 0.917 between the Nonverbal Pain Assessment Tool and the Critical Care Pain Observation Tool. The Chinese Nonverbal Pain Assessment Tool demonstrated significant differences in scores between different states of consciousness and illness severity, supporting its known-groups validity. The Chinese version of the Nonverbal Pain Assessment Tool is a reliable and valid tool for nonverbal pain assessment in ICU patients in China. The Chinese version of the Nonverbal Pain Assessment Tool can assess the pain of patients who cannot use language in ICU, which provides a new valuable assessment tool for Chinese clinicians and nurses in pain assessment and management. Our study followed the STROBE Checklists. Patients actively cooperated and participated in data collection during the implementation of the study.