A method for fabricating a continuous vapor grown carbon fiber, comprising: (a) providing a substrate which has a catalyst on its surface; (b) placing said substrate in a furnace; (c) loading said furnace with hydrogen, ammonia, or combinations thereof; (d) adjusting a temperature of said furnace to 400° C. to 900° C. to proceed heat treatment for 10 minutes to 2 hours; (e) adding a carbon-containing compound into said furnace; (f) adjusting the ratio of said carbon-containing compound and said hydrogen, ammonia, or combinations thereof; (g) adjusting the temperature of said furnace to 500° C. to 1200° C. to crack said carbon-containing compound, and thereby form a carbon fiber.