To construct smart grid, it is essential to utilize advanced technologies in a way that these technologies may ensure the effectiveness of the construction. In term of the development of China's power system, there have been continuous breakthroughs in advanced power electronics. Informatization, digitization and integration have become the dominant theme in construction of the current power system. Viewing from the international trend, however, with the rapid progress of times, a nation's comprehensive strength is manifested by its power system, and almost every country is conducting extensive researches on the development and application of advanced power electronics. The construction of smart grid in our country has its own characteristics, and the paper will focus its study and exposition on this regard. First, we will probe into the definition of smart grid with Chinese characteristics and the energy storage technique, so as to display the advanced nature of our power Electronics. Second, we will explore the battery energy storage system (BESS) and its application from an all-covered viewpoint. Last, a beneficial study will be made on the establishment of the model of BESS. Thus, convincing as the paper's study approach is, it will contribute to the theory and practice of our country's smart grid building.