Abstract: With the opening of the electricity distribution business in China,the grid company takes the responsibility of taking over incremental distribution network.In order to help the state grid enterprises take over the incremental distribution network business,the investment strategy after default service of incremental distribution network is studied.By analyzing the relationship between the economic benefits and effective assets,the growth modes of effective asset after default service are divided into new reconstruction projects as well as early,on-time and delayed replacement/update of equipment.Then an investment optimization model is built to optimize the objective of maximizing the cumulative benefit during the default service period.The examples are calculated,simulated and analyzed in sensitivity with or without consideration of transmission and distribution price constraints.Finally,a series of investment strategy proposals are given,such as the investment in replacement/update of equipment has more direct benefits in the formation of effective assets if replacement time allows.