Objective To retrieve and evaluate the relevant literature on conservative oxygen therapy for critically ill adults，summarize the best evidence，and provide references for clinical practice. Methods We developed a literature search strategy following the "6S" evidence model to retrieve computer decision support systems，guideline websites，and professional society websites，as well as Chinese and English databases，with a search timeframe from the establishment of the databases to April 22，2024. Literature that met the inclusion and exclusion criteria was selected，and two researchers independently conducted quality assessment and extracted and summarized evidence based on professional judgment. Results A total of 17 articles were included，including 4 guidelines，2 evidence summaries，and 11 systematic reviews. 22 pieces of evidence were extracted into 9 categories：oxygenation targets，contraindications，initiation timing，assessment，monitoring，discontinuation timing，precautions，quality control，and bene-fits of conservative oxygen therapy. Conclusion This study summarizes the best evidence for conservative oxygen therapy nursing in adult critically ill patients，which is instructive for medical staff to formulate reasonable oxygen therapy plans，standardize clinical oxygen therapy nursing，and ensure patient oxygen safety. When applying the evidence，it is still necessary to comprehensively judge based on the patients’ specific condition.