In this paper, we study the uniqueness of meromporphic functions and their difference operators. In particular, We have proved: Let $f$ be a nonconstant entire function on $mathbb{C}^{n}$, let $etain mathbb{C}^{n}$ be a nonzero complex number, and let $a$ and $b$ be two distinct complex numbers in $mathbb{C}^{n}$. If $$varlimsup_{rrightarrowinfty}frac{logT(r,f)}{r}=0,$$ and if $f(z)$ and $(Delta_{eta}^{n}f(z))^{(k)}$ share $a$ CM and share $b$ IM, then $f(z)equiv(Delta_{eta}^{n}f(z))^{(k)}$.