The content of data mining usually contains discrete data. To solve this problem, the traditional method is to convert discrete data into digital values. Still it is hard to obtain a meaningful result since the order of discrete data problem area would be damaged. A clustering Algorithm, CLARANS (Clustering Large Applications based on Randomized Search) could avoid this efficiently. The improved and parallel CLARANS introduced here can improve the clustering performance further, and it's able to get better clustering result and as well shorten searching time. This is applied in 110 Alarm System and it turned out to be satisfying.