Based on the cause analysis for the occurring of low frequency oscillation，the analysis methods of low frequency oscillation is concluded，which has two kinds，that is，based on the system measured signal and based on the system mathematical model separately，and the concrete analysis methods is refined． The strategies used in suppressing the low frequency oscillation in AC － DC interconnected system are summarized，and then the current states of the key problems about suppressing the low frequency oscillation are introduced in detail． Finally，the prospects are carried out on the follow － up hot researches of low frequency oscillation．