Inter-subject correlation (ISC) analysis was generally used in naturalistic stimuli studies. Hemodynamic activity in human visual cortex was shown to correlate across subjects during natural viewing a movie clip1,2. This study aimed to investigate the physical properties of naturalistic audiovisual stimuli what cause the correlation across subjects' hemodynamic activity in visual cortex. Naturalistic audiovisual stimuli include multiple physical properties, such as contrast, brightness and flickering frequencies in different frequency bands. To investigate what physical properties of naturalistic audiovisual stimuli cause the correlation across subjects' hemodynamic activity in visual cortex, we used functional magnetic resonance imaging (fMRI) signal in general linear model (GLM) analysis and ISC analysis. First, the results of GLM analysis examining the correlation between the hemodynamic activity of visual cortex and each physical properties of naturalistic audiovisual stimuli turned out: visual cortex was activated by contrast and specific flickering frequencies (0.5Hz, 1Hz, 4Hz, 5Hz, 8Hz and 10Hz), same as the finding of previous studies3-10. And then, we demonstrated significant (p<0.01) t-value in the difference between results of voxel-by-voxel inter-subject correlation before and after removed contrast and specific flickering frequencies in visual cortex. Therefore, we suggest contrast and flickering frequency cause the correlation of hemodynamic activity in visual cortex across subjects. Furthermore, we revealed the selectivity of layer-specific frequency-preference in visual cortex. Same as the finding of the previous study11, we found out that the medial side of occipital lobe was activated by 1Hz of flickering frequency. And the lateral side of occipital lobe was activated by 10Hz of flickering frequency. Interestingly, we demonstrated 0.1Hz of flickering frequency, which has not been studied before, activated the lateral side of occipital lobe. Moreover, we also revealed that thalamus is more sensitive to higher flickering frequency (10Hz). Taken together, our findings provide evidence for contrast and flickering frequency cause the correlation of hemodynamic activity in visual cortex across subjects.