Abstract: Abstract: The resonance frequency of steady-state visual evoked potential was the stimulation frequency corresponding to the maximum visual steady-state response, and the research of SSVEP had a good application prospect in clinical neuroscience and brain computer interface technology. The area of stimulus light source was a factor affecting SSVEP resonance frequency, but little was known about the variation of resonance frequency with the area of light source. In this article, the theoretical research results showed that the change of the area of periodic visual stimulation light source was closely related to the change of SSVEP, and the influence of the stimulation area of different LED sources on SSVEP resonance frequency was studied experimentally. First, SSVEP signals under the stimulus of different light sources were collected and preprocessed by 50 Hz notch, band-pass filter (bandwidth 3-35 Hz) de-noising, de-trending and de-eye-electricity. Then, the average normalized fundamental power of SSVEP under different stimulation frequencies was calculated based on the spectrum analysis of FFT to determine the SSVEP resonance frequency. The results showed that when the light source radius was 5-9 mm and the stimulation frequency was 6-20 Hz, the law of SSVEP resonance frequency changing with the light source area was that when the light source area was less than a certain threshold, the resonance frequency was positively correlated with the light source area. when the threshold was exceeded, the resonance frequency was negatively correlated with the light source area. In addition, this article used flash LED as stimulation source, which could effectively solve the problem that the frequency selection was limited by the screen refresh rate when screen flash was used as stimulation source. The results of this study can provide significant theoretical and experimental basis for the prediction or diagnosis of nervous system diseases and the application of SSVEP in BCI.