Graphene is a new member of the carbon nanomaterial family, and it has many special properties in electronics and optics. Moreover, the performance of the fiber-optic sensors can be improved if their surfaces are modified with a layer of graphene. However, the conventional methods, including liquid phase transfer and vapor deposition methods, for modifying the fiber surface with a layer of graphene have some drawbacks, such as high-cost, difficult implementation, and generating toxic gas. In this paper, a new method for modifying the fiber surface with graphene is proposed, which enables to extract graphene fragments from the graphene dispersion waterand form an accumulation layer of graphene over the fiber surface. Experimental results demonstrate that the accumulation horizon over the surface of a tilted fiber Bragg grating (TFBG) is stable, and it can improve the sensitivity of the TFBG sensor for refractive index measurement with 28%. Furthermore, the experimental results also show that the TFBG with a graphene layer can be made to be a glucose sensor, through attaching pyrene-1-boronic acidon the graphene, enabling a measurement of glucose concentration.