The paper investigates the solute dispersion by alternating current electroosmotic flow (AC EOF) through a slit polyelectrolyte-grafted (PE-grafted) nanochannel with interfacial slip. The methods of series expansion, homogenization principle and Fourier transform are used to solve the unsteady convection dispersion equation. Under the Debye-litickel linearization, analytical solutions for the dispersion coefficient K(t) and mean concentration C-m of the solute are derived. The effects of oscillating Reynolds number Re, the slip length delta, the PEL thickness d, dimensionless parameters lambda and Lambda on K(t) and C-m are discussed in detail. The results indicate that the dispersion coefficient takes positive values for small Re, and the dispersion coefficient will take both positive and negative values for large Re. Furthermore, a critical value of Re is observed, below which the amplitude of K(t) increases and C-m (within the solute band) decreases with Re, and above which a contrary variation tendency about K(t) and C-m is observed. The increase of parameters delta and d, and the decrease of parameters lambda and Lambda will lead to the increment of amplitude for dispersion coefficient, and thereby enhance the process of solute dispersion in a PE-grafted nanochannel. These results can provide theoretical basis and possible application for microscale mixing and drug delivery in physiological systems. (C) 2019 Elsevier Ltd. All rights reserved.