Abstract: Industrial parks have become important experimental areas for electricity reform in China. With the liberalization of incremental distribution market and widespread integration of diversified power sources and loads, the investment interface of park integrated energy system (IES) becomes divided, and the investment entities appear diversified. The analysis of investment benefits thus becomes more complex. This paper firstly analyzes the impact of electricity reform on the operation of park integrated energy system, and proposes four operating modes, including generation-distribution-sales integration, generation-sales integration, distribution-sales integration, and distribution network independent operation; Secondly, a quantitative return on investment model of park integrated energy system is presented for multiple investors, and a case study is conducted. Conclusions are given through a comparative analysis of the calculation results of multiple investors’ return on investment for the four operating modes.