Owing to the advances of computer and communication technologies, clustering analysis on moving objects has attracted increasing attention in recent years. An interesting pattern is to find the moving clusters that are composed of objects moving along for a long period of time. However, a moving cluster inclines to break after some time due to the goal change of some individual objects. In order to identify the moving clusters, we propose a semantically clear definition of moving clusters. Based on the definition, we propose delicate approaches to cluster moving objects. The proposed approaches are evaluated using synthetic data set.