Abstract: In the treatment of heavy ion cancer, it is very important to ensure the quality (uniformity, spot size and position, energy, etc.) of heavy ion beam. In order to meet the clinical requirements for the quality of heavy ion beam, a new proton beam dose distribution imager was designed. The dose distribution imager was based on scintillator, mirror reflector and optical signal acquisition device to transform the heavy ion beam into visible light through sulfur gadolinium oxide scintillator and collect visible light information to control the quality of the heavy ion beam. At the same time, the relative position of scintillator, mirror reflector and optical signal acquisition device can be remotely controlled through the precision electric displacement platform to adjust the equipment vision. The results show that the energy resolution of the dose distribution imager is equivalent water depth of 0.22 mm, the spatial resolution is 0.35 mm, the uniformity of response to a single source is ±3.5% in the 10 cm×10 cm area of the image field of view, and the numerical correction can be carried out by the algorithm. All of the above indicators meet the accuracy requirements of clinical medicine, and can be used for quality assurance of medical proton beam.