Abstract: OBJECTIVE To investigate the similarities and differences of volatile oil components in Album Citri Reticulatae and Cylindricae Citri Reticulatae. METHODS The volatile oil components were detected by GC-MS. The overlapped peak clusters were resolved by alternative moving window factor analysis. The volatile oil components in Album Citri Reticulatae and Cylindricae Citri Reticulatae were analyzed qualitatively and quantitatively. RESULTS Thirty and thirty-two compounds were identified in Album Citri Reticulatae and Cylindricae Citri Reticulatae respectively, representing 92.03% and 94.28%. There were 24 common compounds in Album Citri Reticulatae and Cylindricae Citri Reticulatae, accounting for 89.38% and 92.04% respectively. CONCLUSION There is little difference in the kinds of chemical components between Album Citri Reticulatae and Cylindricae Citri Reticulatae, but a great difference in contents.