The spatial mode-matching problem of Gaussian beams in the preparation of squeezed field with a high compressibility is studied. The study results show that, for a small target spot, the allowed deviation ranges of the waist position and size of the injected beam are small, and the mode-matching efficiency is more sensitive to the deviation of the waist position, while for a large target spot, the situation just reverses. In addition, the ellipticity and astigmatism of the laser spot and the thermal effect of the nonlinear crystal can lead to the decrease of the mode-matching efficiency. An asymmetric cavity can expand the allowed deviation range of the waist position which matches with optical parametric oscillators, which is easier to obtain a higher mode-matching efficiency.