By dividing the business of a power generation group company, the index system of input and output of scientific and technological innovation is established, including production and operation, scientific and technological research and development and technical service. The DEA model is used to evaluate the efficiency of scientific and technological innovation of innovative units in each type of business, and the critical impact indicators of effective units are further mined through the CRITIC method, and the efficiency of scientific and technological innovation is ranked. The innovation data of science and technology research and development units of the group from 2017 to 2019 were selected for empirical research. The research shows that the overall efficiency of science and technology innovation is high. However, there are some problems in some units, such as the fluctuation of the ranking of the efficiency of scientific and technological innovation, the low efficiency of scientific and technological innovation and the declining of the ranking of the efficiency of scientific and technological innovation.