A numerical analysis method (DSMC, Direct Simulation Monte Carlo)[1] was developed to simulate the molecular motion of rarefied gases. In the present paper, numerical approaches by the DSMC method have been carried out. By the computation model of CC-40F carbon coater, the cylindrical deposition machine has axial symmetry; the flows inside the vacuum chamber were analyzed. The substrates were put on the bottom and the fiber near the ceiling in the computational domain. In the computational model, air and carbon molecules are working ones. The effects of the air gas pressure variation in the chamber, the effects of the deposition distance variation and the surface temperature variation of the carbon fiber on thermo fluids phenomena are discussed and visualized. Changing the number density of carbon and air, the temperature of the carbon and the velocity of the carbon in the chamber are discussed. With changing the surface temperature of the carbon fiber, qualitative assay of experiment and simulation result is in similar trend very well. The DSMC method is a forceful tool for the study of rarefied gas flow in vacuum deposition machine.