Hip fracture (HF) is common among older individuals and associated with high mortality, poor vitality and functional impairment. HF patients suffer whole body immunological changes and that lead to severe consequences, including immobilization, physical impairment and a high risk of complications. The objective of this study was to decipher the pattern of dynamic immunological changes, especially in two major T cell subsets, CD4+ CD25+ FOXP3+ regulatory T (Treg) cells and T helper-17 (Th17) cells, and their balance, during the hospital stay and to observe whether blood transfusion could influence these cells and clinical patietns’ prognosis. In this study, ninety-eight consecutive HF patients were initially enrolled, and finally fifty-one patients qualified for the study, and correlation analysis of their clinical parameters was carried out to predict the meaning of their distribution in clinical practice. Our results showed that the frequency of Tregs gradually decreased, while the frequency of Th17 cells slowly increased in HF patients who received blood transfusion. The Treg frequency was inversely correlated with the level of hemoglobin (Hb), and Th17 cell frequency was positively related to fluctuations in Hb levels in HF patients after trauma. HF patients with a better prognosis and survival time showed decreased a Treg frequency and a decreased Treg/Th17 ratio. Transfusion helped reverse the imbalance in the frequencies of Tregs and Th17 cells and the Treg/Th17 ratio and especially contributed to a better outcome in HF patients with moderate-to-severe anemia. In conclusion, a higher frequency of peripheral blood Tregs and a higher Treg/Th17 ratio may be associated with unfavorable outcomes in HF patients, and blood transfusion may benefit moderate-to-severe HF patients rebalance their immune response.