Concerning the time-space-physics risk management of the non-autonomous nonlinear control of under-frequency loadshedding（UFLS） and under-voltage load shedding（UVLS）， this paper reviews its essentials， characteristics， problem-solvingtechniques， current status and prospects. The factors include the objective function， constraints， fault set， control modes，controller location， executing moment and optimization strategies. The conventional setup method for load shedding is based ona single-machine single-load model and cannot satisfy the requirement of modern power systems. A new methodology isproposed， which is based on risk management and quantitative analysis for the time response curves. It employs the ratiobetween safety margin and control cost to guide the risk minimization process. Furthermore， the mechanism of load shedding isinvestigated; coordination between UFLS and UVLS， that between feedback control and feed-forward control， and that amongtransient-term load shedding， middle-term load shedding and long-term load shedding are studied.