Abstract Objective Two dimensional speckle tracking imaging (2D-STI) was used to quantify the longitudinal strain of right ventricle in children with severe pneumonia (SP), and the clinical value and related influencing factors were discussed. Methods 70 children with severe pneumonia were enrolled in the study, and 70 healthy children matched with age and body surface area were selected as the control group. Convention echocardiography and 2D-STI were performed in all the children. The parameters of right ventricular structure and systolic function were obtained: right ventricular end diastolic diameter (RVEDD)、pulmonary artery dimension(PAD）、tricuspid annular plane systolic excursion（TAPSE）、Tei index of the right ventricular、right ventricle fractional area change（RVFAC）、the global longitudinal strain of right ventricle (RVGLS), the global longitudinal strain of free wall (FWGLS) and the global longitudinal strain of interventricular septum (IVSGLS). Results ①Compared with the normal control group, heart rate、respiratory rate、Tei index increased , and TAPSE decreased in SP group (P<0.05), while there was no significant difference in RVEDD and RVFAC between the two groups(P>0.05). ②Compared with the normal control group, RVGLS、FWGLS and IVSGLS decreased in SP group(P<0.05). ③RVGLS、FWGLS and IVSGLS were negatively correlated with age and TAPSE (P<0.05), but positively correlated with heart rate (P<0.05). Conclusion The longitudinal strain of the right ventricle decreases in SP children, which is earlier than the structure and convention function of the right ventricle, and the influence of age and heart rate should be considered in clinical application.