Currently, the distribution network evaluation system is often biased towards a particular aspect such as content planning effectiveness, safety, reliability, etc. The project’s feasibility study is lack of the demonstration of a project’s investment efficiency. And investment decisions are often only simply based on historical data. Facing with these problems, this paper concerns the aspects of the overall investment effectiveness, single project investment effectiveness, investment decisions and establishes the investment effectiveness evaluation and decision-making model of 35 kV or below. This model proposes 19 new indicators to evaluate the effectiveness of single project investment, and gives out the scoring function of calculating the index score. It also gives out evaluation model of calculating distribution network’s scores of the overall investment and monomer investment’s efficiency. According to the investment effectiveness evaluation scores, it determines the level of overall investment effectiveness and set priorities of single project investment. This paper also proposes annual investment decision model based on the grid scale and electricity sales and the score level of annual single project investment benefit. A 35 kV distribution network is taken as an example to test and verify the scientific usefulness of the model. It has great significance to the distribution network’s evaluation and investment decisions.