Objective To develop the Quality Care Behavior Scale for Elderly Care Assistant Nurse and test its reliability and validity. Methods Based on the person-centered care framework, the scale test version was formed by combining the literature review me-thod, semi-structured interview method, expert correspondence and pre-survey. A convenient sampling method was used to select elderly care nursing assistants from 11 nursing homes of Hunan, Hubei and Henan Provinces in central China from April to June 2024 as participants.Totally 330 elderly care nursing assistants were investigated firstly and other 340 were surveyed secondly for scale item analysis and reliability and validity test.Results The finalized Quality Care Behavior Scale for Elderly Care Assistant Nurse includes 26 items in 5 dimensions: holistic care, individualized care, respect for the elderly, positive interaction, and empowerment. The cumulative variance contribution rate of exploratory factor analysis was 67.907%; Confirmatory factor analysis showed that χ2/df=2.607, RMSEA=0.069, CFI=0.914, TLI=0.903, IFI=0.914, which was a good model fit. Criterion-related validity results showed that, the correlation coefficient of the scale score with the Person-centered Care Assessment Tool score was 0.894, the Cronbach′s α coefficient of the scale was 0.948, and the split-half reliability was 0.889. Conclusion The Quality Care Behavior Scale for Elderly Care Assistant Nurse has good reliability and validity, and can be used as a valid tool to assess the quality care behavior of elderly care assistant nurses.