To overcome the shortcomings of metal manufacturing technology in terahertz band,a graphene-based patch antenna which works at 1.0 THz was designed according to graphene characteristics in this operation band.Using graphene surface conductivity model based on random phase approximation(RPA),the relationship of surface conductivity,frequency(terahertz) and chemical potential was studied,and physical parameters of graphene was determined.The antenna structure consists of graphene patches,a polyimide substrate and a ground plane.Through the optimization of HFSS,its dimension is 220 μm×140 μm×9 μm.Graphene-based patch antenna operates in 0.98~1.02 THz,and it has a -10 dB relative impedance bandwidth of 4.0 % and gets a gain of 7.32 dB in maximum radiating direction.In addition,the designed antenna has good advantages of small size,light weight,stable mechanical properties,simple structure and easy integration.