Temporal changes in community composition are a facet of biodiversity change and are referred to as temporal beta diversity. Macroecological patterns of temporal beta diversity have gained attention because of the recent biodiversity crisis. However, no one has seriously studied how temporal beta diversity differs from spatial beta diversity, and the most basic neutral dynamics and temporal beta-diversity patterns remain unknown. Therefore, the present study aimed to reveal the basic properties of temporal beta-diversity patterns under neutral dynamics and identify their differences from those of spatial beta-diversity patterns. A simulation of neutral dynamics was conducted to test the parameter dependency of temporal beta-diversity patterns. Specifically, four fundamental parameters of the neutral model—the fundamental biodiversity number, local community size, mortality rate, and immigration rate—were studied. To describe the form of the simulated temporal distance-decay patterns based on both the Bray–Curtis and Sørensen dissimilarity indices, a three-parameter negative exponential function was fitted for each simulated dissimilarity matrix. The negative exponential function was successfully fitted to all the simulated results and three estimated parameters and the intercepts of the function were plotted along the change in the four parameters of the neutral model. The simulated results demonstrated that upper limits exist in the temporal distance-decay patterns; thus, the temporal distance-decay curves saturate before reaching a completely dissimilar state. Additionally, the form of the curve strongly depends on the four parameters of the neutral model. These results suggest that the relationship between local communities and virtual species pools differs in temporal and spatial beta diversity. Specifically, they suggest that the species pool is spatially variable but temporally constant.