The invention provides a fiber-enhanced resin matrix composite material and a preparation method thereof. The composite material is composed of, by volume, 20-50% of a resin material and 50-80% of a fiber-enhanced material. The resin material comprises 100 parts of a thermosetting resin, 50-200 parts of a curing agent, 1-20 parts of a promoter, 1-20 parts of a releasing agent and 1-10 parts of a filling material. The fiber-enhanced material is glass fiber with tensile strength higher than or equal to 3,500 MPa. The composite material has the advantages of uniform structure, good insulativity, excellent toughness, relatively high strength, high glass-transition temperature, low cost, smooth and clean surface, etc.