Abstract: In this paper, the research on ablation patterns by Lin Tong-ji and his co-workers is introduced. It includes ablation patterns appearing on reentry vehicles, ground-test models and the Jilin Meteorites. It is found that the ablation pattern is controlled by the Reynolds number of the boundary layer on the ablation surface. Two kinds of typical ablation patterns: the ablation wedge and the cross-hatching are studied. Transition Reynolds numbers for both the reentry vehicles and the test models are obtained.