Based on the three-dimensional coupled wave theory and the two-dimensional Runge-Kutta methods, diffraction properties of ultrashort pulsed Gaussian beams by volume holographic gratings (VHG) with truncated boundaries are studied. Effects of the polarizations of the readout beams and the grating boundaries on the intensity distributions of diffracted pulsed beams in spectral and temporal domains are presented, and the effects on Bragg selectivity bandwidth, the total diffraction efficiency of gratings are also given. Simulation results show that the Bragg selectivity bandwidth and the distributions of the diffracted pulsed beams along the output boundary of local holographic gratings in spectral and temporal domains can be improved, and the diffracted pulsed beams with better beam quality and higher diffraction efficiency can be obtained by choosing the truncated parameters of local holographic gratings, controlling the polarizations of the readout beams and choosing the pulse duration of readout pulsed beams.