In this paper, 3D simulation is used in the interaction of the Gaussian laser pulse with plasma electrons that have ramp density parameter in the nonlinear regime of the laser wake-field acceleration (LWFA). The influence of the ramp electrons density parameter on acceleration of the bunch electrons and percent of the trap of electrons at the end of the bubble is investigated. The effect of the density ramp environment as a way of the increase in the deceleration length numerically and eventually the influence of the initial energy and direction of the bunch electrons is proved. By determining the optimum plasma density ramp, the percentage of trapping and spontaneous injection of electrons will increase substantially.
