The effects of ultrasonic irradiation on crystallization behavior of polypropylene (PP)-loaded fillers with nucleating activities, such as sodium benzoate, talc (P), talc (A), and mica, are examined. DSC and WAXD analyses demonstrate that the crystalline structure of PP is changed through ultrasonic vibration. Different nucleating systems have their own specific responses to ultrasound. In sodium benzoate-added PP, beta-crystal appears when ultrasonic with an appropriate intensity was applied, which alters the growth of PP crystals and favors a special crystal transformation (alpha-->beta). On the other hand, ultrasonic does not induce beta-form in the talc or mica system, but prefers crystal growth of (040) plane. Based on the crystalline structure and structures of nucleating agents, the ultrasonic effects in determination of the crystalline preferential growth are analyzed.