In this paper,a coupled level set and volume of fluid,immersed boundary(CLSVOF/IB)method is proposed and implemented into the interFoam solver of the OpenFOAM to simulate the gas-liquid two-phase flows,involving the gas-liquid and fluid-structure interfaces.In the volume of fluid(VOF)method,the multidimensional universal limiter with explicit solution(MULES)approach is used to restrain the volume fraction.An approach for calculating the grid characteristic size for the level set(LS)initial function and the re-initialization equation is proposed in order to make it more applicable to non-uniform grids in the finite volume method.In the proposed CLSVOF method,the continuous LS function is used to calculate the gas-liquid interface curvature so that the surface tension term can be calculated accurately.In the immersed boundary(IB)method proposed in this paper,a virtual forcing term is introduced in the momentum equation to deal with the fluid-structure interface by defining a solid volume fraction,which is convenient for the three-dimensional numerical simulation.For the present flow field solver,an improved scheme of the velocity predictor loop of the PIMPLE framework is also introduced.Two benchmark cases:the Zalesak\'s notched disk and a circular bubble at equilibrium,are simulated first to examine the accuracy of the present CLSVOF method.Then,the effects of several gas-liquid two-phase flows on different fixed structures are investigated.The simulation results are in good agreement with the published numerical and experimental results.