This paper considers the effects of compatibilization with maleic anhydride grafted polypropylene (PP-g-MAH) on the properties of immiscible blends of polypropylene (PP) and nylon 6 (N6). We prepared the blends by three different mixing processes; single-step blending, two-step blending with reactive premixing, and two-step blending with nonreactive premixing, to determine the effective mixing process for fine morphological structure, thermal stability, and mechanical properties. Dynamic melt theological properties were measured to examine the modification of elastic properties by the compatibilizer. In addition, thermal analysis was also carried out to detect the change in-crystallization and thereby to probe the degree of compatibilization. The results show that compatibilized blends prepared by the single-step process exhibit improved phase morphology, thermal stability, and mechanical properties for dried conditions, compared with other blend types. Finally, the water absorption test indicates that the added compatibilizer yields enhanced water resistance in spite of the strong intrinsic hydrophilicity of N6. In particular, two-step blending with reactive premixing is most effective in improving water resistance and reducing degradation of mechanical properties after moisture absorption.