There are some similarities among Karl Popper’s three Worlds in terms of knowledge:quantum step in World 1,World 2 with the generation and structure of man and society,and knowledge step in World 3.There are not only upward causality and downward causality in the three Worlds,but also characteristics of friability,initiative and holographic property from low levels to high levels;World 1,human being as objective target;World 3,knowledge as products of cognition;and World 2,subject of cognition,they are the whole. There are some similarities among Karl Popper’s three Worlds in terms of knowledge: quantum step in World 1, World 2 with the generation and structure of man and society, and knowledge step in World 3. There are not only upward causality and downward causality in the three Worlds, but also characteristics of friability, initiative and holographic property from low levels to high levels; World 1, human being as objective target; World 3, knowledge as products of cognition; and World 2, subject of cognition, they are the whole .