Set thinking includes concept, subset thinking, intersection thinking, union thinking, difference thinking, empty set thinking, one-to-one correspondence thinking and so on.

Set is an important concept in modern mathematics. Set thought is an important symbol of the infiltration of modern mathematical thought into primary school mathematics. When solving some mathematical problems, if we use the set idea, the problems can be solved more simply and clearly. The founder of set theory is German mathematician Cantor (1845— 19 18), and his main thinking methods can be summarized into three principles, namely, generalization principle, extension principle and one-to-one correspondence principle. Since the establishment of set theory, its concepts, ideas and methods have penetrated into all branches of modern mathematics and become the basis of modern mathematics. Euler (1707— 1787), a Swiss mathematician, first used a graph to express the relationship between two nonempty sets, which is now called Euler graph. Wayne, a British mathematician, first used another kind of graph, which can be used to represent any set (regardless of their relationship, they can be drawn in the same style), also known as "venn diagram". Venn diagram is used to represent a set, which helps to explore solutions to some mathematical problems.