The integral SPF/DB(Super Plastic  Forming/Diffusion Bonding) forming process for TC4 titanium alloy panel with large size, dual curvature and non-uniform thickness was investigated, the forming defects including serious fracture (more than six places), obvious shrinkage of grooves (depth of more than 1.1 mm) and badly die attaching appeared after forming due to part size exceeding 1800 mm, complex profile (double curvature, chord height of 330 mm) and uneven wall thickness, and it was difficult to precisely control the distribution of wall thickness after forming by the chemical milling. Therefore, a new process of pre-deformation, chemical milling, diffusion bonding and superplastic forming was proposed, the distribution of wall thickness after superplastic forming was predicted by the FEM simulation, and the feasibility of the process route for chemical milling first and then SPF/DB was proved. Furthermore, the coating accuracy of release agent was improved by the automatic film coating and laser engraving, the panel parts were finally successfully obtained by integral superplastic forming under the condition of 870-930 ℃、1.0-1.5 MPa without defects such as step difference and shrinkage grooves on the surface, the degree of die attaching was smaller than 0.3 mm, the welding rate was more than 90%, the wall thickness distribution was relatively uniform, and the thinning at the intersection of mouth frame was most serious, which was 44.5% of the origin thickness (2 mm). Thus, the main technical requirements of the part were achieved.