Abstract: Considering the new developmental tendency of the state grid including hybrid AC/DC power grids, the access of clean energy, and the power electronics dominated power systems, the changed fault characteristics of modern power systems are analyzed,meanwhile, the challenges and development situation faced by relay protection technology are proposed. Based on this, the principles to be persevered for relay protection technology development are summarized. The emphatic development directions are discussed in detail, namely, the plug-and-play outdoor installation protection, the optimally configured back-up protection, the intelligent operation and maintenance system, three technical supporting platforms of relay protection; the control and protection of high voltage direct current（ HVDC） transmission; the forward technologies of relay protection.