Objective:To explore effects of different flow rates and temperature settings of high-flow nasal cannula oxygen therapy (HFNC) on patients with mild to moderate community-acquired pneumonia (CAP) accompanied by type I respiratory failure.Methods:Using the convenient sampling method, a total of 92 patients with mild to moderate CAP accompanied by type I respiratory failure who were admitted and received HFNC in the Department of Respiratory and Critical Care Medicine in a Class Ⅲ Grade A hospital in Tianjin were selected as the research objects from December 2019 to December 2020. They were randomly divided into 4 groups, including low temperature and low flow rate group (31 ℃, 30 L/min) , low temperature and high flow rate group (31℃, 50 L/min) , high temperature and low flow rate group (34℃, 30 L/min) , high temperature and high flow rate group (34 ℃, 50 L/min) , with 23 cases in every group. Two-factor factorial analysis of variance was used to compare effects of different flow rates and temperature settings of HFNC on the comfort, oxygenation index, respiratory rate and heart rate of patients with mild to moderate CAP.Results:The comfort level of patients in the low flow rate group (30 L/min) was higher than that of the high flow rate group (50 L/min) , and the comfort level of patients in the low temperature group (31 ℃) was higher than that of the high temperature group (34 ℃) . The differences were statistically significant ( P<0.01) . The oxygenation index of patients in the high flow rate group (50 L/min) was higher than that of the low flow rate group (30 L/min) , and the difference was statistically significant ( P<0.01) . Different flow rates and temperatures of HFNC have no interaction effect on the comfort, oxygenation index and heart rate of patients ( P>0.05) , but they have an interaction effects on respiratory rate ( P<0.01) . Individual effect analysis showed that the respiratory rate of patients in the low temperature and high flow rate group (31 ℃, 50 L/min) was lower than that of the high temperature and high flow rate group (34 ℃, 50 L/min) and the low temperature and low flow rate group (31 ℃, 30 L/min) , and the differences were statistically significant ( P<0.01) . Conclusions:For patients with mild to moderate CAP accompanied by type I respiratory failure, the application of HFNC should start with low temperature and low flow rate parameter settings. Under the condition of ensuring the patient's comfort, the overall effect of flow rate and temperature is integrated and the inhalation flow rate of HFNC is appropriately increased, which can increase the clinical effect of high-flow nasal cannula oxygen therapy.