With the main protection designs of seven hydro-generators in Three Gorges Right Bank， Longtan， Xiaowan， Goupitan， Jinanqiao， Laxiwa and Pengshui power stations as examples， the design process of hydro-generators with even or odd branches can be reduced to the main protection design of hydro-generators with two or three branches per phase and the branches per phase are reasonably grouped according to the possible fault features of different hydro-generators， such as adjacent or alternating modes. The summary of corresponding design rules directs the quantitative design for main protection configuration scheme， which greatly reduces the computation workload.