  In this paper, we prove a sharp ill-posedness result for the incompressible
non-resistive MHD equations. In any dimension $d\ge 2$, we show the
ill-posedness of the non-resistive MHD equations in
$H^{\frac{d}{2}-1}(\mathbb{R}^d)\times H^{\frac{d}{2}}(\mathbb{R}^d)$, which is
sharp in view of the results of the local well-posedness in
$H^{s-1}(\mathbb{R}^d)\times H^{s}(\mathbb{R}^d)(s>\frac{d}{2})$ established by
Fefferman et al.(Arch. Ration. Mech. Anal., \textbf{223} (2), 677-691, 2017).
Furthermore, we generalize the ill-posedness results from
$H^{\frac{d}{2}-1}(\mathbb{R}^d)\times H^{\frac{d}{2}}(\mathbb{R}^d)$ to Besov
spaces $B^{\frac{d}{p}-1}_{p, q}(\mathbb{R}^d)\times B^{\frac{d}{p}}_{p,
q}(\mathbb{R}^d)$ and $\dot B^{\frac{d}{p}-1}_{p, q}(\mathbb{R}^d)\times \dot
B^{\frac{d}{p}}_{p, q}(\mathbb{R}^d)$ for $1\le p\le\infty, q>1$. Different
from the ill-posedness mechanism of the incompressible Navier-Stokes equations
in $\dot B^{-1}_{\infty, q}$ \cite{B,W}, we construct an initial data such that
the paraproduct terms (low-high frequency interaction) of the nonlinear term
make the main contribution to the norm inflation of the magnetic field.
