High entropy alloys are composed of multiple primary elements, they outperform many traditional alloys in the cryogenic toughness, high temperature strength and phase stability, and have been the focus of futural development of alloys. This paper summarized the research progress on the strengthening and toughening mechanisms of high entropy alloys in recent 10 years. The typical applications of the strengthening and toughening mechanisms such as dislocation strengthening, twin induced plasticity(TWIP), transformation induced plasticity (TRIP), fined grain strengthening, precipitation strengthening, solid solution strengthening were reviewed. The potentials and limits of these strengthening and toughening mechanisms were analyzed, for example, the first 3 mechanisms only show limited strengthening and toughening effects when used alone, and the last 3 mechanisms show limited toughening effects. The future development directions of strengthening and toughening mechanisms for high entropy alloys were discussed, for example, deeply understanding the mechanisms source and combining multiple mechanisms to achieve best comprehensive properties.