For the study of HTR-PM high temperature gas cooled reactor graphite dust deposition behavior, the graphite dust deposition helium test loop was developed to meet the demand of graphite dust deposition test, which could maximize the simulation of graphite dust in the helium flow propagation and deposition process, with certain wind speed, temperature, at the same time with test parameters control, dust, real-time monitoring, and other functions. At the same time, by analyzing the typical pipeline and valve structure of HTR-PM high-temperature gas-cooled reactor fuel handling system, the simulation pieces of pipelines and valves were designed and developed, which were connected to the helium test circuit for deposition test research. The graphite dust deposition test was carried out, focusing on the influence of gas velocity, gas temperature and deposition structure on the surface deposition distribution and deposition amount of graphite dust. The results showed that the deposition density of graphite dust at the elbow of the pipe was about twice that in the horizontal straight pipe section; the deposition of graphite dust at the flange connection was directly related to the welding weld, and the deposition of graphite dust at the single weld reaches about 0.4 g; the larger amount of graphite dust was deposited around the valve core than the valve disc; the graphite dust deposition increases with the increase of the dust amount, and gradually becomes saturated; after the valve was fully open, the deposition of graphite dust in the valve chamber tended to saturation. The research results provide a technical basis for the radiation protection of external radiation, air pollution and internal radiation protection in the maintenance operation of HTR-PM fuel loading and unloading system, and have an important academic basis for the formulation of HTR-PM radiation protection strategy.