Abstract: There are five types of isochronous stratigraphic interfaces in Qixinghe exploration area, Sanjiang Basin. By Them the coal-bearing sequence is divided into six genetic stratigraphic unites and further into ten subunites. The depositional environment had involved five evolutional stages. Among them the fan-delta abandonment stage was the period most favoured to coal accumulation,and the best place for coal accumulation is on the abandoned fan-delta body.