Objective To investigate the application value of thromboelastography (TEG) in assessing coagulation function in children with severe hemophilia A (HA) after emicizumab (EMI) therapy. Methods A retrospective analysis was performed on the activated partial thromboplastin time (APTT) and TEG testing results of 17 children with severe HA before and after EMI treatment at Shenzhen Children's Hospital from January 2023 to July 2024. Correlation analysis was conducted between coagulation factor VIII (FVIII) equivalent activity and reaction time (R value) measured by TEG. Results After EMI treatment, the mean bleeding rate for children with severe HA was 1.6 events per year, with 15 children (88%) without spontaneous bleeding or joint bleeding. The children with severe HA showed a significant reduction in APTT after EMI treatment (P<0.05), with a significantly shorter APTT than the normal control group (P<0.05). There was no correlation between APTT and FVIII equivalent activity after treatment (P>0.05). After EMI treatment, TEG parameters, including R value, kinetic time, alpha angle (α), maximum amplitude, clot strength, and coagulation index, shifted from a hypocoagulable state before treatment to a nearly normal state after treatment (P<0.05). The R value demonstrated a strong negative correlation with FVIII equivalent activity (r=-0.758, P<0.05). Conclusions The bleeding condition of children with severe HA can be effectively controlled after EMI treatment. Routine APTT testing cannot reflect true coagulation function, whereas TEG testing is clinically valuable in assessing the coagulation function of children with severe HA undergoing EMI treatment.