In this paper, the influence of oxide (SiO2) layer thickness on the different figure of merits of a FinFET is analysed by varying the oxide layer thickness which is present between the gate and the Fin. Here, the overall thickness of the FinFET is taken to be 30nm, and the oxide (SiO2) layer thickness is changed from 0.8 nm to 3nm, and the analog, radio frequency parameters are determined for different structures. The performance parameters like drain current (ID), transconductance generation factor (TGF), transconductance (gm), output conductance (gds), parasitic capacitances like Cgs, Cgd, Cgg, cut-off frequency (fT), gain bandwidth product (GBW) and maximum frequency of oscillation (fmax) are calculated to learn the influence of variation in the FinFET oxide (SiO2) layer thickness. It is detected from the result and analysis that the drain current, output conductance, transconductance generation factor, transconductance and gain bandwidth product improve with decrement in oxide layer thickness. But as a tradeoff, the internal capacitances like Cgs, Cgd, Cgg, maximum frequency of oscillation and cut-off frequency degrade when there is a reduction in oxide (SiO2) layer thickness.