Moderate cross-linked blend (LLDPE-PP) of linear low-density polyethylene (LLDPE) and polypropylene (PP) with benzoyl peroxide (BPO) were prepared by the reactive melt mixing in HAAKE mixer. Effect of LLDPE-PP as compatibilizer on the morphology, crystallization behavior and mechanical properties of LLDPE/PP (87/13) blends were studied using scanning electron microscopy (SEM), polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and mechanical testing machines. The results showed that LLDPE-PP not only improved the interfacial adhesion between the LLDPE and PP but also acted as selective nucleating agent for crystal modification of PP. In the blends, the sizes of LLDPE and PP spherulites became smaller, and their melting enthalpies reduced in the presence of LLDPE-PP. Furthermore, the mechanical properties of LLDPE/PP blends were improved with the addition of LLDPE-PP, and when the concentration of LLDPE-PP was 2 phr, the ternary blend had the best mechanical properties. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2614-2620, 2011