During the 13^th Five-Year Plan period, private enterprises have sprung up in the construction of ethylene projects, and the survival and development of large-scale state-owned petrochemical enterprises were facing great challenges. In order to cope with this challenge and continue to maintain the market share and discourse power of large-scale state-owned petrochemical enterprises in the domestic petrochemical market, large-scale state-owned petrochemical enterprises actively studied the expansion planning of existing Petrochemical bases at the beginning of the 14^th Five-Year Plan. Taking the phase II planning scheme of a petrochemical base as an example, this paper discusses and analyzes the product scheme of a newly built phase II ethylene project of a state-owned petrochemical enterprise.