Abstract: As effective thickness of the target layer in old blocks of Henan oilfield is only about 2-6 m,and the minimum thickness of interlayer is 2-3 m,the difficult points of hydraulic fracturing technique lie in the thin target layer and poor sheltering capacity of the interlayer,which make the hydraulic fracturing treatment break the interlayer easily and increases the layer-to-layer heterogeneity in old blocks.Through careful research and analysis of the factors that influence the height of artificial fracture,hy- draulic fracturing technique of thin layer has been devel- oped and it has been widely applied to 45 wells in Henan oilfield.As a result,the cumulative increased production of crude oil is up to 39000 t.The results show that the hydraulic fracturing technique of thin layer provides im- portant technical support to the stable production of old blocks in Henan oilfield.