<p>Parametric uncertainties in load frequency control (LFC) systems integrated with electric vehicles (EVs) present significant challenges to the accurate computation of stability delay margins (SDMs). The frequency control services are coordinated by communication infrastructure to exchange data between the control center and power generation units. The network-induced delays and parametric variations could negatively affect the stability of uncertain power systems and such challenges could even lead to unstable system behavior. This work examines the SDMs of the LFC-EV system with parametric uncertainty. The exact values of SDMs are first computed by incorporating the Kharitonov theorem and the direct method for a set of controller parameters. Then, the parametric uncertainty margins (PUMs) of the interval frequency control model with EVs are detected to quantify the parametric uncertainty boundaries allowed by the specified controller parameters by utilizing bounded phase conditions. This technique aims to obtain the maximum phase difference among vertices polynomials of the interval LFC-EV system. Finally, the accuracy of both PUMs and SDMs is validated by time domain simulations and Quasi-Polynomial Mapping Root (QPmR) algorithm.</p>