  We obtain the global well-posedness to the 3D incompressible
magnetohydrodynamics (MHD) equations in Besov space with negative index of
regularity. Particularly, we can get the global solutions for a new class of
large initial data. As a byproduct, this result improves the corresponding
result in \cite{HHW}. In addition, we also get the global result for this
system in $\mathcal{\chi}^{-1}(\R^3)$ originally developed in \cite{LL}. More
precisely, we only assume that the norm of initial data is exactly smaller than
the sum of viscosity and diffusivity parameters.
