Abstract: Four strengthening mechanisms of Cu-rich nanoprecipitate-strengthened steel were summarized, including solid solution strengthening, grain boundary strengthening, dislocation strengthening and precipitation strengthening. The evaluation methods for various strengthening mechanisms were thoroughly elaborated based on the characteristics of both matrix and nanoprecipitates. The results showed that all kinds of strengthening mechanisms were closely related to the interaction with dislocations, and different strengthening mechanisms were coupled with each other in the microstructure. This provided theoretical support for the design of noval Cu-rich nanoprecipitate-strengthened steels.