The nucleating activity of side-chain liquid-crystalline copolymer, as new beta-nucleating agent (LCP-NA3), towards isotactic polypropylene (iPP) was investigated by differential scanning calorimetry, wide-angle X-ray diffraction, and polarized optical microscopy. The effect of LCP-NA3 content, crystallization temperature, and time on the phase behavior of the iPP has been discussed. The results indicate that the relative content of beta-crystal mainly depends on LCP-NA3 content, crystallization temperature, and time. A high content of beta-crystal can be obtained by the combined effect of the optimum LCP-NA3 concentration, crystallization temperature, and time. The maximum content of beta-crystal reaches 0.63 when the LCP-NA3 content, crystallization temperature, and time are 0.8 wt%, 130 A degrees C, and 1 h, respectively. In addition, LCP-NA3 is identified to have dual nucleating ability for alpha- and beta-crystals under appropriate kinetic conditions.