Improper design and unreasonable use of terrain may lead to problems such as insufficient space vitality and low use efficiency of urban parks after completion. Therefore, it is significant to carry out scientific and practical spatial vitality assessment in the park design stage. Thus, compared with the traditional spatial vitality research method, the agent-based model forms the overall population preference from the bottom up from the individual point of view, and the simulation results can be used to evaluate the spatial vitality of the park. Based on the disassembly and reconstruction of visitor behavior rules, selection preferences, and spatial environment elements, it built a simulation model (AEABM) in the Unity platform capable of simulating and analyzing the spatial vitality of parks. This model focuses on the quantitative analysis of the spatial dynamism of the park around the spatial vitality characteristics of activity intensity, activity diversity, and activity continuity. Finally, taking Chongqing Central Park as an example, the model simulation results and the actual research results are checked to verify the effectiveness of the AEABM model simulation results. The results show that the simulation results of the AEABM model are consistent with the survey data and initialization parameters and have an excellent simulation effect. However, the simulation results also show that Chongqing Central Park has shortcomings in spatial layout, leisure facilities, and functional design, which limits the spatial vitality of the park.