The present invention provides a resin composition comprising: 1 to 20 parts by weight of a reinforcing fiber; 0.2 to 5 parts by weight of an anti-settling agent; 20 to 40 parts by weight of an epoxy resin; 0.1 to 3 parts by weight of a curing agent; and 50 to 75 parts by weight of a high dielectric constant filler. The present invention further provides a dielectric layer produced from the resin composition and a capacitor comprising the dielectric layer. In the dielectric layer made from the resin composition provided by the present invention, the fibers can be evenly dispersed and can enhance the mechanical strength of the resin composition, and cooperate with the epoxy resin to bring excellent toughness. Therefore, the mechanical strength of the produced dielectric layer can be remarkably improved, and its fragility can be effectively overcome when the dielectric layer is used in the PCB double-side etching process.