Objective To analyze the perioperative bleeding status and its influencing factors in patients with adolescent idiopathic scoliosis(AIS)undergoing orthopedic surgery.Methods A total of 105 patients with AIS who received surgical treatment in the First Affiliated Hospital of USTC,Division of Life Sciences and Medicine,University of Science and Technology of China were selected as the study subjects from February 2015 to September 2022.All patients underwent posterior orthopedic surgery for scoliosis.The periop-erative dominant blood loss volume and hidden blood loss volume were recorded,and multivariate linear regression analysis was used to analyze the related factors affecting perioperative bleeding in patients with AIS orthopedic surgery.Results All patients successfully completed the surgery.The average total perioperative blood loss volume was(456.32±142.30)mL,and the average dominant blood loss volume and average hidden blood loss volume was(255.00±101.26)mL and(201.33±63.07)mL,respectively,accounting for 55.88%and 44.12%of the total blood loss volume respectively.Correlation analysis showed that the total perioperative blood loss volume,dominant blood loss volume and hidden blood loss volume in patients with AIS orthopedic surgery were related to body weight,preoperative Cobb angle,postoperative Cobb angle,corrected Cobb angle,surgical time,number of fusion segments,osteotomy,intra-operative use of tranexamic acid and postoperative drainage volume(P<0.05),and total blood loss volume and hidden blood loss vol-ume were also related to gender(P<0.05).Multivariate linear regression analysis revealed that osteotomy and intraoperative use of tranexamic acid were the main factors affecting perioperative bleeding(P<0.05).In addition,gender was the main factor affecting total blood loss volume and hidden blood loss volume.Body weight and pre-operative Cobb angle were the factors affecting total blood loss volume.Conclusion The proportion of perioperative hidden blood loss volume is high in patients undergoing AIS orthopedic surgery.The risk of perioperative bleeding is significantly increased in patients with osteotomy and is significantly reduced in patients using tranexamic acid during surgery,and the total blood loss volume and hidden blood loss volume are increased in males.