The invention discloses a ladder phase change energy storage accumulation bed system in combination with mechanical ventilation. The system is composed of a ladder phase change energy storage accumulation bed and an auxiliary mechanical ventilation system; according to five construction thermal performance design partitions and actual outdoor thermal environment conditions of the China, two or more phase change energy storage materials with different phase change temperatures are selected, the phase change energy storage material is packaged in a metal ball shell, and according to the phase change temperature ladder change, the material is placed in the ladder phase change energy storage accumulation bed, the auxiliary mechanical ventilation system is provided with four stations accordingto the running principle, the ladder phase change energy storage accumulation bed is combined with mechanical ventilation, night natural ventilation, a solar air heat collection device and an air electric heating device under different stations to achieve efficient running of the full-year station, the auxiliary mechanical device is adopted to improve the utilization efficiency of renewable energysources, and the building energy consumption is effectively reduced while indoor human body heat comfort needs are met.