  Multi-qubit quantum Rabi model, which is a fundamental model describing
light-matter interaction, plays an important role in various physical systems.
In this paper, we propose a theoretical method to simulate multi-qubit quantum
Rabi model in a circuit quantum electrodynamics system. By means of external
transversal and longitudinal driving fields, an effective Hamiltonian
describing the multi-qubit quantum Rabi model is derived. The effective
frequency of the resonator and the effective splitting of the qubits depend on
the external driving fields. By adjusting the frequencies and the amplitudes of
the driving fields, the stronger coupling regimes could be reached. The
numerical simulation shows that our proposal works well in a wide range of
parameter space. Moreover, our scheme can be utilized to generate two-qubit
gate, Schr\"odinger states, and multi-qubit GHZ states. The maximum
displacement of the Schr\"odinger cat states can be enhanced by increasing the
number of the qubits and the relative coupling strength. It should be mention
that we can obtain high fidelity Schr\"odinger cat states and multi-qubit GHZ
states even the system suffering dissipation. The presented proposal may open a
way to study the stronger coupling regimes whose coupling strength is far away
from ultrastrong coupling regimes.
