Objective To develop an evaluation tool for the screening of high risk population for oral complications in critically ill patients, which can be performed accurately and scientifically. Methods Basing on the related foreign oral assessment scale, combined with the method of brainstorming, expert consultation, method of clinical status and so on, the item pool of the assessment scale was determined. Five nursing experts and two oral experts assessed the content validity and 50 ICU nurses were tested. Then, the screening accuracy of the assessment scale was proved by application in 100 critically ill patients selected randomly. Results The Cronbach’s a coefficient of final version of the High Risk Assessment Scale for Oral Complications in Critically Ill Patients (including seven parts contents of oral health assessment and oral pH value test) was 0.815, the content validity index (Sr-CVI/Ave) was 0.932. The results of 50 nurses to the 91.2% assessment items of the assessment scale were very important and important. For screening related indicators of oral complications in high-risk patients, the sensitivity of the assessment scale was 97.53%, the specificity was 94.11%, the positive predictive value was 98.75%, the negative predictive value was 88.89%, and the crude agreement was 95%. Conclusion There are good reliability, validity and a high accuracy of screening test in the High Risk Assessment Scale for Oral Complications in Critically Ill Patients. It can be used for screening patients at high risk for oral complications in critically ill patients, and help clinical nurses to complete the oral health status of the critically ill patients quickly.