The invention discloses a ray digital imaging mounting platform for a fillet weld of a heat exchanger. The platform is used for mounting a digital imaging system (5) in an automatic detection system for ray digital imaging of the fillet weld of the heat exchange tube. The platform comprises a support unit (1), a lifting unit (2), a rotating unit (3) and an angle control unit (4), wherein the lifting unit (2) is fixed on the support unit (1); and the rotating unit (3) and the angle control unit (4) are fixed on the lifting unit (2). The platform disclosed by the invention is capable of realizing the functions, such as, inserting, pulling, fixed-angle rotation, inserting in-place detection and movement between holes of the digital imaging system (5). The platform is coordinated with the support unit (1), the lifting unit (2), the rotating unit (3) and the angle control unit (4), so that the full-automatic ray digital imaging detection for the fillet weld of the heat exchanger can be realized.