The ultrafast particle population transfer in a ■-type three-level atomic system driven by linearly polarized chirped Gauss femtosecond laser pulse is investigated by using numerical solution of the Schrdinger equation without the rotating wave approximation(RWA).It is shown that the population transfer is mainly determined by the Rabi frequency(intensity) of the driving laser field and chirp rate,and the ratio of two dipole moments and the pulse width also have obvious effect on the population...