Abstract: Biyang sag hydrocarbon distribution is influenced by oil generation central area,which shows belt-shaped distribution around oil generation central area,presents "the full basin" oiliness.The forward structure belt is the main accumulation area,on longitudinal "layer upon layer" oiliness,main oil layer is He III up-segment 2-4 oiliness.The oil deposit type are various,the north and south difference is big and assumes supplementally,structure lithologic deposit primarily.Using Weng model,the field size order method,Gompertz model,broom model and so on,Biyang sag reservoir growth trend has been predicted.It is thought Biyang sag reservoir quantity is 4×108 t,residual resource quantity is 1.4×108 t,the exploration potential is big,in the near future the high proven reserves rate can still be maintained.