The aim of study is to use erythrocyte ABO genotyping to assist serological typing in the identification of suspected ABO subtypes. Nine samples with discrepancies in ABO serological forward and reverse typing were subjected to ABO 6–7 exon sequencing, and their respective results were cisAB01O1, Bw12O2, Ael05B, Bel03O1, Ael05O1, B(A)04O1, B(A)02O1, and two cases of O1O2 weak antibody for the reverse typing test. The ABO genotyping and serological ABO forward and reverse typing were combined for subtype identification. In the results of ABO genotyping, cisAB and B(A)04 are only found B gene in genotyping, thus the presence of A subtype B was excluded. The samples with a weak antibody for serological O type in reverse typing were tested ABO genotyping to exclude subtype A or B. We summarized a combination of ABO genotyping and serological typing can be used for identification of suspected ABO blood groups.