The electro-optical properties of polymer dispersed liquid crystals (PDLCs) depend on dispersion structures and nematic alignment which can be controlled by taking proper liquid crystal/polymer mixtures and process conditions. To achieve excellent electro-optical properties such as low driving voltage, good contrast ratio and negligible hysteresis, we have developed optimization procedure. Under the optimized conditions, PDLC of low threshold voltage less than 3.1 V, high contrast ratio more than 150 and negligible hysteresis were obtained.