Objective To construct and validate a risk assessment tool for inpatient unplanned extubation. Methods Through systematic literature review, analysis of current situation of unplanned extubation, group discussion and expert meeting, an item pool for Risk Assessment Score for Inpatient Unplanned Extubation was established. By using Delphi Method and superiority charting, the risk assessment tool was finalized. A total 201 patients from top 8 departments with highest unplanned extubation case counts were measured with the tool to test its reliability and validity. ROC curve was described to identify the cutoff value of the tool. Results The Risk Assessment Score for Inpatient Unplanned Extubation includes 6 factors totaling 25 items. The content validity index of the tool was 0.896 and the test-retest reliability coefficient was 0.931. The area under the ROC curve was 0.760［P=0.002, 95%CI（0.638,0.881）］; the best cutoff value was 6.5,with the sensitivity being 0.692, and specificity 0.670, and the Youden Index 0.362. Conclusion The Risk Assessment Score for Inpatient Unplanned Extubation has good validity and reliability. It can be used to predict the high-risk population of unplanned extubation, and serve as an effective assessment tool for nurses to accurately identify inpatients at high risk of unplanned extubation.