Conductive polymer composites (CPCs) filled with carbon nanotubes (CNTs) have attracted increasing amounts of attention due to their easy fabrication methods and wide range of application. With an appropriate amount of CNTs in polymer matrix, the composites possess flexibility and piezoresistivity at the same time. These attributes have been utilized for developing smart materials which are able to measure their own strains through the variations in their electrical resistance. In this study, the different preparation method of CNTs filled thermoplastic vulcanizates (TPV) based on PP/EPDM blends were demonstrated to be vital for preparing TPV-based strain sensors with tunable sensitivity. Morphology observation of TPV without CNTs loading revealed that there exist huge difference between the two methods, i.e. the EPDM phase size is only 550nm for the one-step method while that for the two-step method is 228ƒÝm. Furthermore, it was found that the CNTs particles for the two methods were almost selectively located in the PP matrix. Meanwhile, the sample for the one-step method owned a lower conductive percolation threshold, only 0.65 wt%, accompanied with a better stable and durable resistivity-strain behavior , while the sample for the two-step method showed a higher conductive percolation threshold of 11.8wt%, which was accompanied with higher sensitive resistivity-strain behavior. Further, the tensile model for TPV was used to expound the novel tunable sensitivity of resistivity-strain behavior caused by the EPDM phase size for TPV. This study provides a guideline for the preparation of a tunable sensitivity of resistivity-strain behavior TPV strain sensors. Keywords: Conductive polymer composites (CPCs); Thermoplastic vulcanizate (TPV); Resistivity-strain behavior.