Objective To identify ABO blood group in a case of blood group serological inconsistences. Methods ABO blood group of the specimen was identified by blood group serological, and the genotype was determined by PCR-sequence specific primer (SSP) sand ABO gene direct sequencing. Results Serological test showed the characteristics of B(A) subtype. PCR-SSP test result was B(A)04/O1. Sequencing analysis indicated that the 6th exon had 261delG and 297A>G mutations and the 7th had 526C>G, 640A>G, 657C>T, 703G>A, 796C>A, 803G>C, 930G>A mutations, and the blood type of the sample was B(A)04/O01. Conclusion A case of blood group serological identified as B(A) was confirmed as B(A)04/O01 by PCR-SSP and ABO gene direct sequencing method.