the parameter sitting for K-mean in auto model for

Ammar_Almasri

when i do experimental on data set using K-means the cluster size never changes and center point as well. why they didnt change if they select ceroid randomly 

Telcontar120

It completely depends on the dataset characteristics.  Some datasets are "stable" in the sense that there is one clear solution for a k-means of a given size k, which will always converge to that solution.  Others are not, in which case rerunning the clustering algorithm can lead to different results.  
You can try setting the local random seed to different numbers to see whether that makes a difference.