In this paper, peristaltic flow in a tube due to the waves of contraction is studied applying a modified immersed boundary-lattice Boltzmann method. The lattice Boltzmann method is used to describe the flow filed, and the modified immersed boundary method is used to couple the moving boundaries to the surrounding fluid. This method introduces the velocity induced by the flexible tube wall into the lattice Boltzmann equation, which replaces the conversion between the fluid velocity and the force induced by the deformation of the moving boundaries in the traditional immersed boundary-lattice Boltzmann method. We analyze the streamlines and velocity distribution, then systematically investigate the effects of variation of the relevant parameters such as the amplitude ratio and frequency of the traveling wave, viscosity of the fluid and wavenumber on the flow of the peristaltic tube. The comparison between the simulative and existing results shows that the method is reasonable and effective.