Objective：To investigate the postoperative X-ray change of simple humeral bone cysts with different activity levels and its association with prognosis and clinical significance. Methods：The clinical data of children with humeral bone cysts who underwent surgical treatment in our hospital from January 2012 to April 2018 were collected，and the association between postoperative X-ray change of lesion and prognosis was analyzed in children in the active or latent stage of the disease. The Neer standard was used to evaluate activity level and treatment outcome，and a statistical analysis was performed. Results：A total of 66 children were enrolled and they were followed up for （22.05±4.34） months. Among these children，38 were in the active stage，among whom 6 achieved com－plete response，13 achieved partial response，15 had no response，and 4 experienced recurrence；28 were in the latent stage，among whom 27 achieved complete response and 1 achieved partial response. There was a significant difference in cure rate between the active group and the latent group[50%（19/38） vs. 100%（28/28）， ?字2=19.660，P=0.000]. A total of 19 children in the active group and 28 children in the latent group achieved complete or partial response，and there was a difference in healing time between the active group and the latent group[（11.47±3.65） months vs. （8.32±2.26） months，t=1.779，P=0.082]. Among the 38 active lesions，16 changed into latent lesions after surgery and all of them were cured，while among the 22 persistently active lesions，only 3 were cured（?字2=24.290，P=0.000）. Conclusion：Active lesions of humeral bone cysts tend to have a poor prognosis than latent lesions，and the active lesions that change into latent lesions after surgery tend to have a good prognosis. Patients in the active stage should be closely followed up in clinical practice，and individualized treat－ment should be given based on imaging features and changes.