The inflation process of large-scale or extra large-scale parachute was investigated. The Arbitrary Lagrangian Eulerian (ALE) Method-a Fluid- Structure Interaction (FSI) model, was used to simulate the inflation process of a main parachute (a ringsail parachute, which was used in manned spacecraft) in an infinite mass situation. The dynamic relationship between canopy shape and flow field was obtained, and the adverse inflation phenomena such as asymmetric inflation and whip were observed in simulation results. The “bottleneck” phenomenon in inflation process was found and verified by physical tests. Based on the analysis of calculation results, it is found that the large canopy area, the complicated canopy structure or high inflation speed can block the air mass into the parachute, which can cause the “bottleneck” phenomenon. But the necessary occurrence conditions of the phenomenon need to be studied in future. The present work is significant for explaining parachute working mechanism and preventing its failure.