Chemical-looping gasification (CLG) is a promising way for syngas production as the integration of chemical looping and gasification technology, which can avoid air separation with a high hydrogen extent in syngas. In this work, the multi-fluid model with chemical kinetics is employed to simulate the CLG performance in a bubbling fluidized bed reactor using char as solid fuels. The distributions of gas compositions and temperatures are predicted. The interactive mechanic between oxygen carrier and solid fuels is analyzed. In addition, the impacts of operating parameters on mixing behaviors of particles and gas products during the CLG process are evaluated. The results demonstrate that the decrease of operating velocity and oxygen carrier particle size will reduce the syngas production. An increase of oxygen carrier size weakens the mixing degree of the binary mixture, whereas increasing the gas inlet velocity can restrict the segregation of the binary mixture.