Abstract: The nonconforming EQrot1 element was applied to a kind of nonlinear moisture migration equation. The supercloseness property was obtained by using mean-value approach and two special properties of this element: (I) the consistency error is one order higher than its interpolation error in the energy norm when the exact solution belongs to H3(Ω); (II) the interpolation operator is equivalent to its Ritz-projection operator. Furthermore, through interpolation post-processing technique, the global superconvergence result was derived.