Abstract: Linear transformer driver (LTD) is a new pulsed power technology with novel topology. It can generate fast high power pulse by dividing energy storage capacitor into many small ones, and gain high voltage by induction addition. One of the key characters and technique difficulties of LTD is the trigger theme. This paper introduces the concept of extendable trigger technology. An extendable trigger unit with 40 output cables was designed and tested. When the Marx was charged by ±60 kV, the trigger unit with a 75 Ω load output a peak voltage of 106 kV, and the risetime was 27 ns (10%~90%), FWHM was 110 ns. The trigger time difference of the four laser-triggered gas switches (as the output switches) was less than 3 ns under the conditions of about 70% working coefficient and total laser energy of 55 mJ.