As an important data analysis method, rough set theory can be used to analyze data with uncertainties. Rough set is able to acquire knowledge by the indistinguishable relationship among data objects without any prior knowledge. Rough set theory provides a new theoretical means for solving soft computing problems and has a wide application space in data mining. Meanwhile, the fuzzy C-means clustering algorithm is sensitive to noisy points and has low convergence speed. In order to deal with the above problems, a novel fuzzy clustering algorithm based on rough set and inhibitive factor is proposed. According to the related concepts of rough set theory, the membership model of fuzzy C-means algorithm is redefined. Besides, an inhibitive factor is set to improve the convergence speed of the algorithm under the premise of guaranteeing the clustering effect. K E Y W O R D S fuzzy clustering, inhibitive factor, membership degree, rough set 1 INTRODUCTION There are many cluster analysis approaches in the data clustering field. From the view of the membership degrees of data sample, cluster analysis can be divided into two categories. One is the hard clustering analysis, the other is the soft clustering analysis, also known as fuzzy clustering analysis. 1 Hard clustering is a kind of strict division, which aims to divide every data sample into a specific cluster. Its division mechanism is very clear with only two membership degrees: 0 and 1, which means a sample can only belong to a certain class or not at all. This clustering method is too strict to deal with some data at the boundary, which could easily cause errors. Soft clustering is more tolerant for the division of data and divides them into different clusters according to their membership degree. The traditional fuzzy clustering method is sensitive to noise data, and the accuracy of clustering is often not good enough when dealing with complex data sets. Although some data objects are divided into a certain cluster, it is not obvious that they belong to that one. Rough set theory can deal with the fuzzy and uncertain problems. The idea of inhibitive factor comes from the suppressed fuzzy C-means clustering algorithm (S-FCM). 2 The essence of S-FCM is prizing the biggest membership and suppressing the others. By choosing the reasonable a parameter, S-FCM converges faster than FCM under the precondition of not decreasing clustering performance. In this article, the related work about fuzzy clustering algorithm based on rough set is overviewed in Section 2. In Section 3 the related concepts of rough set theory and fuzzy method are introduced. Section 4 designs a new calculation method of fuzzy membership degree. At the same time, an inhibitive factor is used to improve the convergence speed of the algorithm, and then a fuzzy clustering algorithm based on rough set and the inhibitive factor is proposed. The experimental results and analysis are given in Section 6. Section 6 gives the conclusion of this article.