Background: Recent neurophysiological studies have evaluated neural synchronization using wavelet transformation and the phase-locking factor (PLF). However, mathematical details of PLF and statistical processes to examine the significance of PLF have remained unclear. The present report discusses the significance level of PLF. Methods: Mathematization of PLF was performed, and results for PLF simulation were obtained, using a program for retrieving randomized samples from complex numbers within a complex unit circle in MATLAB software. Results: For PLF mean and variance, a simulated curve was fitted to the theoretical curve. Computer simulation might show that we need 100 data points and 10 subjects to use Rayleigh distribution. Conclusions: The present report demonstrates the significance level of PLF and the amount of the samples. This report may provide an additional potential application for the assessment of how neural activities are locked to stimulation, for example, to selection of the channel of magnetoencephalography study.