New structure patterns of metal panel are used in modern life such as Truss Core Panel (TCP). It is used as flooring or wall material in train, car, aircraft, and buildings etc. at present. Beyond the traditional material, the new patterns have lighter weight and harder stiffness. However, in general, there are difficulties in forming truss core panel, which should be getting forming limit and developed. In this paper, firstly forming limitation is discussed for tetrahedral truss core. Secondly improved hotforming simulation was set for improvement.