The invention discloses a T5 fluorescent lamp conversion support. A circuit board is arranged in the chamber of the support; a conversion device is provided with a plug corresponding to a T8 lamp tubesupport and a socket corresponding to a T5 lamp tube; the plug and the socket are connected with the circuit board via wires respectively; the circuit board is provided with a T8 to T5 lamp tube parameter conversion and start circuit, and the circuit comprises a first diode of which two ends are connected in parallel with two poles of the filament at one end of the T5 lamp tube, a second diode ofwhich two ends are connected in parallel with two poles of the filament at the other end of the T5 lamp tube, and a resonant capacitor of which two ends are connected in series between two cathodes of the first diode and the second diode. The anode of the first diode is connected in series with the first resonant capacitor and is connected with two pins of the plug on one converter via a selective switch, and the anode of the second diode is connected with two pins of the plug on the other converter. The T5 fluorescent lamp conversion support can directly replace a T8 fluorescent lamp, does not need to modify the prior lamp circuit, and has low cost.