The low frequency oscillation characteristics of East China power grid after commissioning of Huainan-Shanghai ultra-high voltage（UHV）are researched.With a review and summary of several low frequency oscillation cases of East China power grid occurred in recent years，this paper summarizes the main low frequency oscillation modes in East China power grid based on the analysis of different typical operation modes.In addition，the impacts of significant maintenance on low frequency oscillation are analyzed.Special research on oscillation mode of UHV generators to East China power grid are carried out，and the importance of power system stabilizer（PSS）are emphasized.Comparative analysis between time and frequency domain are carried out，and engineering experiences in time domain analysis are introduced.The influence of governing system on low frequency oscillation are researched，coping strategies in practical engineering are put forward.In the end，focus and direction of low frequency oscillation research are forecasted.