An infrared electromagnetic metamaterial multichannel absorber is desig ned based on graphene,alternating grating and Al substrate.The Finite-Difference Time-Dom ain (FDTD) method is used to simulate the influence of the thickness of the graphene layer and the grating structure parameters on the absorption spectrum,and then the optimal design str ucture is obtained. The results show that the absorption spectra of FP cavity resonance and magnetro n resonance are sensitive to the thickness of the graphene layer and the height of the grating. As the thickness of graphene increases or the height of the grating decreases,the left frequency sh ifts to the left quickly,and the interference peaks drift slightly to the right,with the absorp tion rate greatly increasing.When the grating period decreases or the duty ratio increases,the l eft frequency shifts to the right obviously,while the interference peaks are almost unchanged.At th e same time,the peak positions of the interference peaks shift linearly to the right as the refr active index of the environment increases,so it can be used for high-sensitivity sensing of refrac tive index or liquid and gas concentration.