A broadband near infrared (Nir) absorber with a five-layer substrate / gold film / Silicon Dioxide / graphene / grating structure was designed based on a dumbbell grating.In this p aper,the time domain finite element method (FDTD) was used to simulate the variation of absorption spectrum bandwidth under different structure parameters,and the structure design was optimized.The results show t hat the absorber exhibits perfect absorption characteristics in the near-infrared band,and when the thic kness of the silicon dioxide layer is 200nm,the dumbbell grating function is 0.2x²⁺ 0.07,the thickness is 300nm,and the period is in the range of 0.89－0.95μm The absorption bandwidth can be up to 300nm,and the absorption can be increased by introducing a single layer of graphene between the buffer layer and the grating. The absorber has many potential applications in the fields of medicine security,broadband communicati on and stealth technology.