Abstract: ：Analyses the advantages and disadvantages of several existing methods for description of distance between clusters，based on it，presents a calculation method for distance between clusters based on gravitation model. This method is an important improvement for direct addition of gravitation value between each particle， which simulates the synthetic principle of force in physics. Theoretical analysis and computing results show the presented method is more applicable than direct addition of gravitation.

Key words: clustering, distance between clusters, gravitation, integral