Abstract: Objective To explore the characteristics of sublingual microcirculation in children with community acquired pneumonia （CAP） in different age groups. Methods The medical records including sublingual microcirculation of 41 children with CAP in the Bayi Children's Hospital affiliated to the seventh medical center of Chinese PLA General Hospital from September 2018 to September 2019 were retrospectively analyzed.According to age,the children were divided into preschool children （age ranging from 1-6 years） and school-age children （age ranging from 7-14 years）,characteristics of growth and development index,macrocirculation index and microcirculation index were compared between the two groups.T test or mann-whitney rank sum test were used for inter-group comparison,Pearson correlation coefficient analysis was used for correlation analysis. Results A total of 41 children were included in the study,with an average age of （6.6±2.6） years old,ranging from 14 months to 14 years,with male accounting for 48.8% and female for 51.2%.The difference in body temperature and peripheral capillary oxygen saturation （SpO₂） between the two groups was not statistically significant （P>0.05）,while the school-age children had statistically significant lower heart rate,and higher systolic blood pressure,diastolic blood pressure and mean arterial pressure compared to the preschool children （all P<0.01）.The hetergeneity index （HI） and hetergeneity index small （HIs） of preschool group was higher than that of the school-age group and the differences were statistically significant （P<0.01,respectively）.Other microcirculation indexes （DBs,PPV,PPVs,AV,AVs,TVD,PVD,PVDs） showed no statistically significant difference （P>0.05）.Correlation analysis of microcirculation index with age,BMI,body temperature,heart rate,systolic blood pressure,diastolic blood pressure and mean arterial pressure in the children showed that HI and HIs of the children was significantly correlated with age （P<0.05）.Their correlation coefficients r were-0.420 and-0.435,respectively,indicating a moderate negative correlation,while other indexes showed no significant difference. Conclusion The differences of macrocirculatory index in children with CAP at different age do not affect the level of microcirculatory perfusion.Sublingual microcirculation of HI and His is higher in preschool children than in school-age children.