Using the quantum channel estimation method, studies the dynamical evolution of quantum Fisher information(QFI) with respect to decoherent rate of two interacting qubits under pure dephasing channel. Numerical results show that the quantum Fisher information always increases from zero to a maximum value before rapidly decays, finally decays to zero, a larger decoherence rate leads to smaller quantum Fisher information and shorter decay time to zero, and also show that the maximum quantum Fisher information is not enhanced by promoting the degree of entanglement in the initial input state.