Most of the fixed word combinations were recognized as a kind of idiom in phraseology. They consist of several words, but their meaning cannot be inferred from, or is not the sum of the meanings of its component words. There are many types of fixed word combinations, for example, collocations, idioms, conventional expressions, routine formulas, proverbs etc. There are quite many various definitions of fixedness and idiomaticity and it is difficult to list them consistently. Many fixed word combinations are more or less fixed in form, but there are also a great number of idioms that are variable. Furthermore, there are different degrees of idiomaticity. In this paper, we focused on the essential features, stability or fixedness and idiomaticity. A fixedness is considered based of different flexibility of the syntactic distribution in corpus. An idiomaticity is reflected linguistic meaning type and is considered the correlation between whole meaning and extralinguistic reality and whether to present information in dictionary, etc. According to this feature, we mainly analyzed word-combinations which is consisted of two linguistic signs. Through this study, fixed combinations are divided into three types and each type have two sub-types, so it was classified into a total of six types. This study is expected to be able to understand and explain systematically the principle and meaning of the fixed word combinations, which are difficult to treat lexicographically and pedagogically.