: Addition of fillers to silicone rubber (SR) insulating materials has gained wide interest. Therefore, preparation of micro and nano composite materials will be helpful both for the users and manufacturers for improving electrical and thermal performances of insulators for high voltage applications. This paper deals with the experimental studies on the morphological, electrical and thermal characteristics of low weight % Zeolite (Z) filled nanocomposites and highly filled microcomposites. For the performance comparison breakdown strength and thermogravimetric analysis (TGA) test have been done on the SR specimens. Scanning electron microscopy (SEM) studies were conducted to understand the dispersion of the filler and the changes in surface morphology in both microcomposite and nanocomposite specimens. The results indicate that the electrical and thermal performances of microcomposites and nanocomposites are increased with the increase of filler concentration. Maximum breakdown strength value and TGA value were obtained from nanocomposite with 7 wt% filler concentration.