Disclosed is a fluorescent tube of thick and thin diameters, which relates to the illumination field, a polar or non-polar fluorescent tube comprises a glass tube and a core column, the inner wall of the glass tube is coated with a fluorescent powder layer, the glass tube is composed of a main glass tube and a pin glass tube, wherein the main glass tube is a thin-diameter glass tube, the pin electrode glass tube of an electrode lamp or the pin glass tube of a non-polar lamp is a thick-diameter glass tube, the thick glass tube and the thin glass tube are in integral structure, the diameter of the thin glass tube differs by 1-4mm from that of the thick glass tube. The invention is high in production efficiency, simple in technique, fine in illumination efficiency and long in service life.