Based on the two-dimensional (2D) coupled-wave theory, the temperal and spatial diffraction properties of an overlapping finite size volume holographic grating read by an ultra-short pulsed laser beam are studied. The temporal and spatial distribution of the diffracted and transmitted light intensity along the output boundary of the grating is obtained. Taking LiNbO3 as an example, the effects of the two-dimensional grating size, incident angle, the grating's refractive-index modulation and the pulse width of the input ultra-short laser pulse upon the intensity distributions of the diffracted and transmitted pulsed laser beams along the output boundary of the grating, pulse shaping and the total diffraction efficiency are given. By comparison with the diffraction properties of one-dimensional volume holographic grating read by ultra-short pulsed laser beams and the diffracgtion properties of the grating read by continuous waves, the method of choosing grating parameters and input conditions to obtain the diffracted pulsed laser beams with uniform-distributed pulse and larger total diffraction efficiency is presented.