Electron standing wave (ESW) states excited in the vacuum gap near sample surface by operating the scanning tunneling microscopy in field emission regime have been widely used to probe the local electronic properties of novel materials and structures. For accurate interpretation of the ESW states spectra, a simple numerical approach is developed based on a one-dimensional model, and the transmission coefficient is accurately calculated using the transfer matrix method. Effects correlated with the potential distribution in the tunneling gap are discussed. By this method, main features of the experimental spectra obtained on Si(111)7 × 7 surfaces are successfully simulated. Factors affecting the spectra are discussed. Copyright © 2012 John Wiley & Sons, Ltd.