The activation of aOE (c) c + a > non-basal slip system can help to improving the mechanical properties of Magnesium alloys. The activation conditions of aOE (c) c + a > non-basal slip system in Mg alloys are reviewed, such as the addition of lithium elements, increasing temperatures, and regions of stress concentration, and so on. Moreover, the article summarizes our results from the work on Mg alloys using equal channel angle pressing with back pressure, and points out that aOE (c) c + a > non-basal slip systems also become active much easier under hydrostatic pressure, which will help to open new window to explore the basic physics of the activation of non-basal slip.