Exposure to ionizing radiation combined with traumatic tissue injury is an important life-threatening condition found in the civilian populations after nuclear and radiological events. The significance feature of radiation combined injury (RCI) is the severe combined effect, which makes the injury more complicated. At present, there are limited measures available to treat RCI. Here we show that a chimeric protein dTMP-GH, fusing human growth hormone (hGH) with a tandem dimer of thrombopoietin mimetic peptide (dTMP), could be an effective therapy agent for RCI in a mice model. In this study, using a RCI mouse model exposed to ⁶⁰Co γ-ray photons (6.0 Gy, 0.3 Gy/min) followed by a 20% total-body-surface-area burns (henceforth called: RB-CI) was established. Administration of dTMP-GH (200 ug/kg) for 10 consecutive days beginning at 24 h after injury improved survival rate during a 30-day observation period compared with the control vehicle group. dTMP-GH treatment also showed enhanced bone marrow hematopoiesis recovery determined by peripheral blood analysis and bone marrow histopathology. Meanwhile, dTMP-GH treatment accelerated skin wound closure and mitigated ileum injury in the RCI model. These results suggest that dTMP-GH may prove to be an effective therapeutic drug for RCI.