The mechanism of the fast ignition in laser fusion and ultra-intense and ultra-short-pulse laser plasma interaction are analysed theoretically and simulated numerically.Two-and Two and half-dimensional cloud-in-cell simulation codes are developed and simulation results for ultra-intense and ultra-short-pulse laser propagating in an inhomogeneous plasma and the boring velocity and the depth of the hole are presented,as well as the parameter index of the laser device of fast ignition in laser fusion.