Electronic transport properties in an Al cluster are investigated theoretically in this paper. We propose a possible illustration of Coulomb blockade based on variable electrostatic potential ( ESP). Density functional theory ( DFT) was used to achieve the global minimum structure and wave function for analyzing the ESP and density of states ( DOS) of Al68 in different charged states. Al68 is able to contain multiple electrons. According to the calculation of systematic energy and surface ESP, respectively, the surface of Al68 presents a 0-6.33 eV ESP barrier after electron injection, which is 0 eV at first. The probability density of flow of electrons was calculated under one-dimensional model with double barriers. Expected results were obtained, containing a nonlinear relationship between J and V and flow density steps. Moreover, an assumption is proposed associated with nonlinear conductance phenomenon of zero-dimensional nanomaterials. Significantly, Al films with different thicknesses were prepared by the low vacuum physical vapor deposition ( LVPVD) method, exhibiting novel fluorescent behaviors. In addition, the I-V curve of a 25-nm Al film exhibited two steps at 7 and 27 V, respectively, which meant that the step effect was caused by Coulomb blockade, in accordance with the theoretical calculation. [ABSTRACT FROM AUTHOR]