Nowadays, high thermal conductive and good electrical insulating materials gain attention for compact and sustainable design in power electronics instruments like transformers, switches, cables. To cater for these needs, Boron Nitride (BN)/Banana Fiber (BF)/Epoxy based polymer composite is proposed which exhibits good electrical resistance and low dielectric constant. Banana fiber is chosen as it contains few lumens among the fillers and offers good mechanical strength. Boron Nitride and Banana fiber are reinforced with epoxy resin to form highly insulating polymer matrix composite material. Various samples are fabricated, containing 1/3/5 μm BN particle size, 1/3/5 wt % of BN and 0/2/4 wt % of BF derived from Response surface methodology based Box Behnken Design model using design of experiments approach. Further, Analysis of Variance is performed to obtain optimized levels of parameters using regression equation in MINITAB software. Also, experimental results and optimized results are compared leading to error analysis. High resistance of 346.68 Giga-ohms (86.67 ×10⁹ Ω-m resistivity) and minimum dielectric constant of 1.143 are obtained for combination of 3 wt % of BN, 2 wt % of BF and particle size of 3 μm which is considerable for good insulation purpose.