β-Thalassemia is a genetic disease characterized by the defective synthesis of the hemoglobin tetramer β-globin chains. So far, a number of mutations have been identified and associated with this genetic disease. A high incidence of thalassemia has been found in Guangxi (China). Herein, we report a case of a patient with slightly increased HbA2 levels (4.6%). Based on the clinical data and laboratory findings, the patient was diagnosed with β-thalassemia. Routine genetic screening tests were negative. Sequencing revealed an A deletion at codon 30 (HBB: c.91delA) and the genotype of this patient was βCD30M/β. This mutation changes the splice receptor site of intron 1 from AG to GG, which likely abolishes splicing at the normal 5′ splicing site and may cause β0-thalassemia. Based on hematological and clinical evaluations, this novel mutation was regarded as a β0-thalassemia allele. A homozygosity or compound heterozygosity of this mutation and other β0-thalassemia alleles can lead to severe thalassemia disease.