Abstract: The diffusion bonding/stretching forming process of TC4 titanium alloy honeycomb core was simulated by ABAQUS finite element simulation software, and the optimal stretching length was obtained by the simulation. The cell outline, wall thickness distribution and diffusion bonding interface morphology of honeycomb core were studied by diffusion bonding/stretching forming tests. The results show that after TC4 titanium alloy laminate was obtained by diffusion bonding at 920 ℃/3 MPa/60 min and then stretched for 75 mm at 800 ℃ and strain rate of 1 mm·s^-1 to form honeycomb core. The regular hexagonal cells were formed in the honeycomb core, which verified the feasibility of preparing honeycomb core by diffusion bonding/stretching forming process. The cells of honeycomb core middle part had good quality and relatively high dimension accuracy, with the average height of 16.2 mm, average width of 21.5 mm, bending round corner of 2.5 mm, and the maximum thinning rate of 5.37%. There was no obvious hole defect in the welding area of laminate, and the welding rate exceeded 95%; after stretching there was no tear in the diffusion bonding area, and no cracks in the bending round corner area.