In this paper the effect of a space charge on the dynamics of relativistic particles in a laser channel has been considered. We derived the expression for effective potential describing the dynamics of charged particles including into the study the interaction of particles with each other. Analysing general concepts on the distribution of a particle beam in a channel, we have formulated the condition, which determines the limits of applicability of the perturbation theory when space charge is taken into account. Keywords: Ponderomotive potential, Lasers, Channeling, Quantum particle, Space charge