In order to obtain strong multiple Fano resonances, a metasurface composed of asymmetric nanosheet heterodimer was designed in the paper. Based on the finite element analysis method, the physical mechanism of Fano resonances was analyzed by the hybridization theory, and the different Fano responses resulted from different Fermi levels, structures parameters were analyzed. Results show that when the Fermi level of the graphene nanosheet increases, the Fano resonance peaks blue shift, and the intensity of graphene responses is enhanced, which causes that the local effect and absorption are enhanced accordingly. At the same time, with the increase of the asymmetry of the size and position of the nanosheet heterodimer, the asymmetry of Fano resonances also increases. The Fano resonances based on the simply graphene nanosheet heterodimer array are expected to be widely used in biosensor and related fields. The study provides theoretical reference for further experimental research.