We study two superconducting charge qubits sharing a large Josephson junction with transient effects considered for the case of the linear sweep model to explore the influence of a time-varying field on the entanglement of the qubits. We show that the fluctuations in the entanglement can be controlled by the transient effects. Moreover, the time-averaged entanglement oscillates smoothly and then fluctuates with the increasing influence of the transient effects.