In this paper, the tunneling effect as the main mechanism for charge transferring in polymer/carbon nanotubes (CNT) nanocomposites (PCNT) is correlated with interphase percolation. Soft-core and hard-core models express the percolation threshold based on a previous report. Furthermore, the tunneling effect is related to the interphase layer around the nanoparticles and the excluded volume and percolation threshold are defined for this case. The calculations of all models are compared to the experimentally measured percolation threshold in some samples. The predictions of soft-core and hard-core approaches deviate from the low percolation threshold in PCNT. It is found that the model assuming the interphase as tunneling distance can properly describe the low level of percolation threshold in PCNT. Based on this model, the effects of main parameters on the percolation threshold and the electrical conductivity of PCNT are described. The predictions demonstrate that the thin and long CNT together with the thick interphase show positive impacts on the percolation threshold and conductivity.