With the all-round development of efficiency power plants（EPPs）， in the process of electric power system planning or operation analysis， the impact of EPP should be taken into account. This paper presents a brief description of the basic theory of the equivalent energy function method for probabilistic production simulation of a power system. At the same time， a more complete exposition of EPP is made that focuses on the capacity， classification， output curves， cost and other related concepts of EPP. This paper also proposes the approach of a variety of EPPs involved in power system production simulation and the calculation process of EPP involved in the power system production simulation. Finally， the impact of the introduction of EPP is analyzed and quantitatively calculated with an example.