A multi-tube fluorescent discharge lamp, which is constructed of multiple glass tubes of different caliber in coaxial structure, the both sides of the inner most tube are connected to a cathode respectively, by isolating, perforating and blocking the discharge path, forming a successive discharge path, and coating phosphor on surface of the discharge tubes. The Invention can then have more fluorescent area than a conventional fluorescent lamp of the similar size and higher lumen as well as power transfer factor. Compared with the power consumption of a conventional fluorescent discharge lamp, the Invention therefore has higher luminous flux.