The selective distribution of aluminum borate whisker in isotactic polypropylene (iPP)/syndiotactic polypropylene (sPP) blends was studied. For iPP/sPP/whisker composites, whiskers are distributed in iPP phase, which follow the theory of interfacial tension. When Irganox 1010 is introduced into the composites, the distribution of whiskers is changed from iPP phase to sPP phase. The results of contact angle tests indicate that the characteristics of the whisker surface are modified by Irganox 1010 and the interactions between the whisker and the matrix are dominated by van der Waals type power law. An entropy-penalty process dominates the change of distribution of whiskers in the composites. The DMA tests show that the loss modulus of composites is improved when whiskers distribute in sPP phase. (C) 2009 Published by Elsevier Ltd.