The dynamics of a modulated electron beam in a plasma barrier is studied via computer simulations using the 1D and 2D models for a wide range of parameters, such as initial beam modulation depth, electron beam current density and plasma density profile. The effects of competition between the resonant mode of a beam–plasma system and space charge wave of the beam at the modulation frequency are discussed. The influence of the beam–plasma turbulence mode on the evolution of the modulated beam is studied. The evolution of the velocity distribution function of the modulated beam during its motion in the dense plasma is considered, and the influence of background plasma inhomogeneity on the modulated beam evolution is also studied. For 2D simulation the influence of the beam transversal restriction is discussed. The simulation results are compared with previous laboratory experiments.