The entanglement dynamics problem between two non-identical qubits in the Tavis-Cummings model without rotating wave approximation is discussed by the extended coherent state (ECS) method. The effects of the qubits with different transition frequencies but with a same coupling strength and the optical fields on the entanglement evolution between two qubits are investigated. The research results show that, in the case of the weak coupling, the entanglement evolution between two qubits is the same when the transition frequency of one qubit is identical to the optical field frequency but the transition frequency of another qubit is symmetric detuning from the optical field frequency. In contrast, in the case of the strong coupling, the entanglement evolution between two qubits is no longer same under the cases of two symmetric detuning due to the effect of the non-rotating wave term.