The low frequency oscillation characteristics of East China Power Grid after commissioning of the first ultra-high voltage alternating current (UHVAC) project—the Huai-Hu UHVAC project are studied. Several low frequency oscillation cases occurred in East China Power Grid in the past few years are reviewed and summarized. Based on the analysis of the different typical operation modes, the main low frequency oscillation modes in East China Power Grid in the early stages of development of ultra-high voltage (UHV) are summarized, and the impacts of the significant power grid maintenance on low frequency oscillation characteristics are analyzed. Besides, the oscillation mode of UHV generators to East China Power Grid is researched, and the importance of the power system stabilizator (PSS) is emphasized. Furthermore, the comparative analysis between the time domain and the frequency domain is carried out, and the influences of the governing system on low frequency oscillation characteristics are revealed. Finally, both the focus and the direction of low frequency oscillation research are presented.