In this paper we consider the case that three identical two-level atoms are trapped in a single-mode cavity which is in a weak coherent state initially, and there is an interaction between two atoms. The tripartite entanglement dynamics among atoms is studied. The influences of atom-atom coupling constant and intensity of the cavity field on the tripartite entanglement among atoms are discussed. The results obtained using the numerical method show that the tripartite entanglement among atoms is strengthened with the increase of intensity of the cavity field; on the other hand, it is weakened with the increase of the coupling constant between atoms.