Recently, a new alloy design strategy, i.e., high-entropy alloys (HEAs), was proposed based on the principle of equal-molar or near-equalmolar fraction for all the components. Different from traditional alloy design strategy which usually blends with one or two elements as the principal constituent, such revolutionary alloy design concept leads to the unique atomic structure, which giving rise to unique mechanical, physical and chemical properties of HEAs. However, mechanical properties of HEAs need to be further improved, e.g., FCC (face-centered cubic)-structured HEA usually has a large ductility but a low strength, BCC (body-centered cubic)-structured HEA usually has a high strength but a low ductility. Second phase strengthening has been widely applied in HEAs and was proved to be effective to strengthening or toughening HEAs. However, due to the unique atomic structure of HEAs, behavior and mechanism of second phase strengthening were different from that in traditional alloys. Here in this short review manuscript, the current research status and underlying mechanism of second phase strengthening were briefly reviewed. The future perspective of second phase strengthening in HEAs was also discussed.