The effects of slip condition and particles concentration are investigated on the peristaltic flow of a Newtonian suspended fluid flows through a channel under different parameters. The walls of the channel are assumed flexible with an external uniform magnetic field applied perpendicular to the walls. The equations of motion are solved analytically using the perturbation method to yield the pressure, streamlines and the velocity distributions for both fluid and dusty particles. The governing equations of the flow through magnetic field are solved under the effect of concentration, wave number, amplitude ratio, Reynolds number and slip condition. The resulting relations for velocity and pressure gradient are plotted for various pertinent parameters. It was observed that in the case of positive pressure gradient, the reversal flow intensity increases with increasing the particle concentration, while it decreases with increasing the magnetic field. Furthermore, thereversal intensity increases with positive pressure gradient. For negative pressure gradient, the intensity increases with increasing the magnetic field. On the other hand, the critical reflux pressure gradient decreases with the presence of suspension and magnetic field, while the critical reflux pressure increases with slip condition. The streamlines are also computed and drawn for some physical quantities to discuss the trapping phenomenon.