A granular flow target coupled with a beam window was studied. The beam window isolates the accelerator from the target, making the system more secure and flexible. Preliminary analyses for the beam window and beam tube, including neutronics, thermal hydraulics, and structural mechanics were performed by Geant4 and ANSYS. The effects of geometry and coolant flow direction on the temperature field and the stress distribution of the beam window are studied. The results show that the maximum temperature can be reduced by 13% through optimization. Comparing the thermal deposition distribution of the beam tube with and without the beam window, we find that there is an extra peak due to the beam window. In addition, the effect of the cooling pattern on the temperature distribution of the beam tube is also studied. The results show that it is reasonable to arrange six U-shaped cooling channels. Detailed analyses show that the material temperature and the mechanical property of the beam window and beam tube meet the design standards, which confirm the possibility of granular flow target with a beam window for engineering application.