Background Environmental, socioeconomic and genetic factors all are associated with respiratory diseases. ABO blood group may contribute to the underlying susceptibility to respiratory diseases. Our study aims to investigate the association between the ABO blood groups and the susceptibility to respiratory diseases and the subsequent severity of the diseases. Methods We constructed a large retrospective cohort study of blood donors in Shaanxi, China, to investigate the impact of the ABO blood group on the risk of hospitalisation due to respiratory diseases. Reasons, duration and discharge status of hospitalisation were collected between January 1, 2012, and December 31, 2018. Results Of 1,686,263 enrolled participants (680,788 females), 26,597 were admitted to hospital for respiratory diseases. Compared with blood group O, blood groups A, B and AB all demonstrated a higher risk of diseases of the upper respiratory tract (ICD10: J30-J39) (ARR 1.139 95% CI [1.106–1.225]; 1.095 [1.019–1.177]; 1.178 [1.067–1.30], respectively) and the highest ratio was observed in participants of blood group A aged ≥55 years (1.456 [1.038–2.042]). Conversely, blood group A was found to have a lower risk (0.86 [0.747–0.991]) in influenza (J09-J11) and blood group B was lower for pneumonia (J12-J18) (0.911 [0.851–0.976]) when compared with blood group O. The duration of hospitalisation was significantly different across the blood groups in J09-J11 and J30-J39 (P<0.05). No significant difference was observed in the discharge status across blood groups. Conclusions The blood group appears to be a prognostic factor in differentiating the occurrence of specific respiratory diseases and duration.