The stratigraphic units and thickness of Putaohua oil reservoirs in Daqing Placanticline become gradually numerious and large from north to south, thus the sequence stratigraphic division and correlation turn more diffi- cult. To make clear of the developed mode of Putaohua oil reservoirs in the Placanticline, with the help of the inte- grated use of seismic, well-logs, core, mud logging and regionally geological data and so forth, the studies of the sequence stratigraphic characteristics of PI Formation are conducted. The study results show that the very complex sequence stratigraphic developed mode of Putaohua oil reservoirs in the Placanticline is generally resulted from the combined action of following four modes : 1 ) the mode of foreset ; 2 ) the stratum developed mode of truncation ; 3 ) the mode of lamina overlapped in low accumulation space (AS) ; and 4) the mode of river parting and swinging channel. The sequence stratigraphic developed mode of the target layers in Lasaxing Oilfields possesses important significance for the studies of the stratigraphic sequence isochronal correlation and depositional laws.