Abstract: Hot rolled H-section steel is a kind of highly efficient and economical sectional material.It has a wide flange,good lateral rigidity and better performance in bending.Currently homemade H-section steel is classified as Wide,Medium,Narrow and Thin sections.Provisions of H-section steel beam on stability in Code for Design of Steel Structures are borrowed from those of I-section or buildup section beam.Contribution of good sectional properties of H-section steel to stability is not embodied.It is necessary and urgent to research H-section and I-section steel beam separately so that control condition of stability for homemade H-section beam is obtained and the code is improved timely.Starting from the principle of over-all stability,it calculates reduction coefficients of H-section steel beam according to formulas in the code,and presents control condition of stability more suitable for homemade H-section beam.The conclusion is a basis for the revision of Code for Design of Steel Structures and a reference for steel constructions.