Abstract:The analysis of joints occurrence in rock mass is an important basic work for mechanical and hydrodynamical behaviors analysis of rock mass. Traditional analysis of plots methods is inadequate to this work;therefore a fuzzy clustering analysis is developed. Both the advantages and disadvantages of fuzzy clustering method and ISODATA fuzzy clustering method are analyzed;then the two fuzzy clustering methods are combinated into a synthetical fuzzy clustering method;and a procedure of the synthetical fuzzy clustering method is proposed. A case study shows that the results of the synthetical fuzzy clustering method are reasonable and reliable.