Abstract: Entanglement is used to measure correlation between entangled subsyste ms. In this paper, we use Von Neumann entropy to study evolution of the entangle ment for two coupled dual level atoms in the process of interaction between ato m s and the field initially prepared in a coherent state. We show that the entangl ement is related to coupled strength, detuning and intensity of the field. For t wo atoms initially prepared in the Bell basis, with coupled strength between two atoms and detuning between atoms and the field increased, entanglement and its oscillating frequency will increase. But increasing the intensity of the field l eads to decrease of entanglement.

Key words: entangled state, Tavis Cummings model , entanglement