Abstract: A compact low impedance pulse forming module in long pulse linear transformer driver(LTD) working repeatedly is designed by integrating Blumlein pulse forming network（PFN）, switch and linear transformer. In order to optimize configuration, reduce distribution parameters and improve waveform, each module consists of two 20 Blumlein PFN which is designed in L-type. A coaxial switch drives two PFNs, and high voltage pulse feeds symmetrically primary coil of LT. A built-in laser trigger switch is developed for cutting down inductance and decreasing risetime of pulse. Comparatively this switch shortens its down-lead by 50%, and risetime is reduced by 10%. The LTD experimental device of two stages produces pulses with voltage of 240 kV and duration of 180 ns at 25 Hz repetitive rate in a resistance load of 18.5 .