The purpose of this study is to design an optimal strontium carbonate (SrCO3) crystal which can effectively compensate the orientational birefringence of polymers. Additionally, we try to compensate large positive birefringence which polycarbonate (PC) exhibits. Furthermore, we analyze the orientational behaviors of the crystals in biaxially drawn polymer films. As a result of the measurement of orientational birefringence of the polymer films doped with SrCO3 with various average sizes and aspect ratios and estimation of orientation function of the crystals, we found out that SrCO 3 with higher aspect ratio and larger size had higher compensation efficiency for the birefringence. As a result of measurement of transparency, we found out that the copolymer film doped with SrCO3 with higher aspect ratio and larger size was less transparent. Therefore, it was suggested that we should design an optimal crystal for particular purposes from the standpoint of the birefringence compensation efficiency and transparency when we apply this method to an optics application. Additionally, we succeed in designing a zero birefringent PC by doping with SrCO3. Furthermore, we found out that SrCO3 was aligned in a perpendicular direction to the thickness direction and was randomly oriented in planar direction in biaxially drawn polymer films.