The orientation and structure of a potentially optimal interface between ZnO film and Si (100)(Si) , substrate has been determined by a good-matching-site (GMS) approach. The GMS are calculated as a function of the rotation angle between ZnO and Si lattices with the axis of [11 (2) over bar0](zno)//[001](Si). The optimal interface (10.0990)(Si) with maximum GMS density are predicted when the GMS thresholds, i.e. the misfit displacement between two corresponding lattice points in ZnO and Si, is from 15-25%. When the threshold is out of this range, the GMS distribution is not consistent with the configuration of the good matching patches on the interface. Then, the step structure on the interface can be defined according to distribution of the GMS clusters. The predicted orientation and step structure of the interface are consistent with those calculated by the Delta g parallelism rules. (C) 2015 Elsevier B.V. All rights reserved.