The high-energy αparticles produced by deuterium-tritium fusion are the primary heating source for maintaining high temperatures in future tokamak plasma. Effective confinement of αparticles is crucial for sustaining steady-state burning plasma. The initial energy of αparticles is $ 3.5 {\text{ MeV}} $ . According to theoretical calculations, it takes approximately 1 second to slow down αparticles through Coulomb collisions to an energy range similar to the energy range of the background plasma. In the slowing-down process, some αparticles may be lost owing to various transport processes. One significant research problem is how to utilize αparticles to effectively heat fuel ions so as to sustain fusion reactions in a reactor. Assuming local Coulomb collisions and neglecting orbital effects, a classical slowing-down distribution for αparticles can be derived. However, considering the substantial drift orbit width of αparticles and the importance of spatial transport, numerical calculations are required to obtain more accurate αparticle distribution function. In this study, the particle tracer code (PTC) is used to numerically simulate the slowing-down process of αparticles under different scenarios in the Chinese Fusion Engineering Test Reactor (CFETR). By combining particle orbit tracing method with Monte Carlo collision method, a more realistic αparticle distribution function can be obtained and compared with the classical slowing-down distribution. The results show significant differences between this distribution function and the classical slowing-down distribution, particularly in the moderate energy range. Further analysis indicates that these disparities are primarily caused by the strong radial transport of αparticles at these energy levels. The research findings hold profound implications for the precise evaluating of ability of αparticles to heat the background plasma. Understanding and characterizing the behavior of αparticles in the slowing-down process and their interaction with the plasma is critical for designing and optimizing future fusion reactors. By attaining a deeper comprehension of the spatial transport and distribution of αparticles, it becomes possible to enhance the efficiency of fuel ion heating and sustain fusion reactions more effectively. This study establishes a foundation for subsequent investigations and evaluation of αparticles as a highly efficient heating source for fusion plasmas.