The frequency response of electro-optic sampling with a β-barium metaborate (β-BaB₂O₄, BBO) crystal in the near-infrared band was investigated based on numerical calculations. The detection performance of the electro-optic sampling in the measurement of a near-infrared few-cycle laser pulse was also analyzed. The study then examined the pulse distortion of a few-cycle laser pulse resulting from detection under different thicknesses of BBO crystals, while also considering the central frequency shift and change in bandwidth. The changes in bandwidth and central wavelength based on the BBO thickness levels were given with laser wavelengths in the range of 0.9 μm to 2.1 μm. The results show that these changes are less than 0.1% when the BBO is 10 μm. They then increase when the BBO thickens. When the BBO is 200 μm, the observed change in bandwidth is 20%, and the shift in the central wavelength is 6%. This study provides a theoretical reference for extending electro-optical sampling detection technology to the near-infrared band and provides guidelines in detecting and calibrating few-cycle laser pulses in the area of high-field physics.