We present the results of numerical study of the generation process of difference frequency radiation (DFR) arising via interaction of mutually orthogonal linearly- polarized a few-cycle laser pulses propagating in a quasiphase- matching (QPM) GaAs crystal. Considered the interaction of pulses having the central wavelengths of 1.98 μm, duration of 30 fs with the electric field amplitude 200 MV/m, propagating along the normal to the <110> plane. The period © of QPM GaAs crystal in numerical simulations varied from 20.89 μm to 53.23 μm. It is shown that by changing the grating period of QPM GaAs crystal from 23.02 μm to 37.29 μm it's possible to improve efficiency of QPM generation of DFR in 5.48 μm ÷ 10.12 μm spectral range at least by 8 dB in comparison with the generation of DFR in bulk crystal GaAs in the same spectral range.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.