The characteristics of high-order harmonic generation (HHG) driven by 5 fs laser pulses interacting with argon under tightly focused geometry are investigated in this paper. By carefully optimizing parameters like dispersion, gas pressure and gas cell position, the enhanced HHG with nearly one order of magnitude in a range of 60-73 eV is observed. Based on single atom approximation and Maxwell propagation equations, numerical simulation is conducted to compare with the experimental characterization with proper parameter. It is proved that the phase-matching plays a crucial role in this phenomenon showing that the theoretical results are in agreement with the experimental results.