The utility model provides a novel fluorescent tube, aims to solve the problems of low luminous flux and short service life of a fluorescent tube in the prior art, specific improvements are made to the integral fluorescent tube, and a structure totally different from an existing fluorescent tube is provided. The novel fluorescent tube consists of an outer glass tube (1), internal coating powder (2) for the outer glass tube, a ring-shaped filament (3), an inner glass tube (5), external coating powder (4) for the inner glass tube, a reflecting film (6) and a heat-insulating material (7), and the fluorescent tube is characterized in that the outer wall of the inner layer and the inner wall of the outer layer of the double-layer glass tube are coated with pure trichromatic fluorescent powder, and the thickness of the coating powder on the inner wall of the outer glass tube is reduced by half; the heat-insulating material is loaded in the internal space of the inner glass tube; the inner wall of the inner glass tube is coated with the reflecting layer; and the tube cap is an H-shaped and ring-shaped glass tube cap provided with the ring-shaped filament, thereby forming a device for preventing mercury spots and black spots.