Based on the basic principle of nonlinear strong-field effect induced by the free electron interaction with intense laser fields, a scheme to trap the high-energy electrons by four propagating laser beams has been proposed to improve the total probability of nonlinear process by prolonging the interaction time of free electron and strong field. The mechanism is based upon the electron scattering by intense laser beams. The numerical simulation results show that the interaction time between electrons trapped and central optical field has been prolonged.