Because of hidden and harmful feature, it is very difficult to solve the question of hide failure in protective relaying, it needs not only technology means but also management means. In this paper, hide failure is classified as software, hardware and relay setting according to origins of failure, then reasons and measures of avoiding or decreasing hide failure are discussed for each kind of origins from two aspects of technology and administration. The paper analyses the influence of development of future power system on hide failure of protective relaying, including digital transformer substation, wide-area protection and distributed generation. Research shows that the mentioned classified method is steady, which has adapted well to development of power system, and it is useful and all-around to avoid or decrease hide failure from two aspects of technology and administration.