Based on the diffusion approximation theory, when the laser pulse transmitting through the turbid media, its energy will be attenuated and the pulse shape will be changed by the scattering and absorption. In this paper, Mathematics equations of the ultra short Gauss laser pulse in different pulse width tp are given, the reflective pulses with the boundary condition of semi-infinite homogeneous media are discussed. We get the simulation results of reflective intensity and the reflective pulse shape of different tp based on the diffusion equation. From the results, we know that the ultra short Gauss laser pulse will be widened by the diffusive scattering. Besides, we find that the various medium parameters will influence the reflection of the Gauss laser pulse very differently. With the boundary condition of semi-infinite homogeneous media, the influence of the absorption, the scattering, and the anisotropy coefficient will be also changed by the different tp of ultra short Gauss laser pulse. All the conditions mentioned above have been investigated in the present paper. This study will be very useful for the measurement of optical properties of tissue.