The invention provides a stepped heat storage system and a stepped heat storage method. The stepped heat storage system comprises a solid heat storage heat exchanger (A), a phase change heat storage heat exchanger (B), a fused salt steam superheater (C), a main pipeline and a bypass pipeline. The stepped heat storage system and the stepped heat storage method have the advantages of stability of heat energy output, low cost, a simple structure, flexible operation and control and the like, adapt to heat storage and heat exchange of a large solar thermal power station heat storage system, adapt to heat storage of unstable industrial waste heat recovery, and have great significance to full utilization of renewable energy sources and waste heat.