Vertical-cavity surface-emitting lasers (VCSEL) are widely used in short-reach optical communication links and interconnects because of their low energy consumption, low threshold current, and high modulation speed. Wet etching and dry etching are two processes for high-speed VCSEL fabrication of mesa structure, which will influence the size of oxide layer. In this paper, the impact of the oxide layer on the parasitic capacitance is analyzed. Compared to the wet etching process, the oxide capacitance of 7 μm oxidized aperture VCSEL is reduced from 902.23 fF to 581.32 fF, and the capacitance associated with the intrinsic region is also reduced from 320.72 fF to 206.65 fF. The small-signal modulation response of high-speed VCSEL with GaAs quantum wells fabricated by wet and dry etching process were measured respectively, and the bandwidth of 7 μm oxide aperture VCSEL with dry etching was increased to 16.1 GHz.