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Vagueness or uncertainty is a conception associated with the set. At present, there have been many painstaking mathematical tools to solve this problem, such as fuzzy set, rough set, intuitionistic fuzzy set and so on. As an another kind of mathematical tool for dealing with uncertainty, soft set proposed by Russian scholar Molodtsov in 1999. Without any restrictions to objects, a soft set approximately describes an object with two parts which are predicate and approximate value. In addition to soft set, the other mathematical tools to processing uncertainty are all lack of parameterized tools, therefore it can not be good enough to solve complex practical problems. As the only theory now can overcome the above-mentioned difficulty, soft set gets a very wide range of applications. But in the process of solving practical problems, we will find that many attributes are ambiguous and soft set itself to the description of attributes is accurate. To overcome this difficulty, the article combines the soft set with the fuzzy set, and gets a new mathematical model to solve the actual problems better. Intuitionistic fuzzy set adding a new attribute parameter called nonmembership function is put forward by Atanassov. It is a tool which can describe the“neither-nor”fuzzy conception, and can depict exquisitely fuzzy essence in the real world. So this article combines soft set with intuitionistic fuzzy set, and constructs a new mathematical model, namely intuitionistic fuzzy soft set, then the properties are discussed. Rough set theory which is proposed by professor Pawlak, and it is another mathematical tool to deal with fuzzy and uncertain knowledge. its main idea is to find the decision-making and classifying rules by knowledge reduction with keeping the classifying capability. Rough set theory play a key role in the fields of data mining, pattern recognition, decision-making analysis and so on. So in this article, we try to combining soft set with intuitionistic fuzzy rough set, and constructing two newmathematical tools. Hope that in the future study, we can discover new advantages in sloving practical problems. Finally, this article makes some discussions for the algebraic structure of soft set, and combines fuzzy soft set with group to get a new kind of algebraic structure -inverse fuzzy soft group, then its nature is analyzed.