Passive cooling technologies can significantly reduce the increase in refrigeration energy consumption caused by high outdoor air temperatures in summer, offering substantial energy-saving potential. Radiative sky cooling and evaporative cooling, in particular, are favored by researchers due to their low carbon footprint. However, most existing studies focus on combining a single passive cooling technology with air conditioning, which limits the stability and coefficient of performance of the system’s performance. To overcome this limitation, this paper proposes a novel passive cooling-assisted air conditioning integrated system (PCAAC) that integrates radiative sky cooling, evaporative cooling, and air-cooling. A distributed parameter model of the system is established and validated using MATLAB. The effects of outdoor air temperature, solar radiance, and relative humidity on the system’s steady-state performance and exergy are analyzed. The simulation results show that the system exhibits excellent adaptability to outdoor environmental changes, significantly reducing energy consumption. This study not only confirms the superiority of air conditioning integrated with passive cooling technologies in various outdoor environments but also provides a reference for the further application of passive cooling technologies in the field of air conditioning.