Abstract: A new circuit comprising a Marx-bank and an avalanche transistor chain absorber obtains a high voltage pulse, the risetime of which is less than 6ns, the downtime less than 3ns, jitter is less than ins and voltage around 3 7kV.This producer is used to select a single mode-locked optical pulse on ND:YAG active-passive mode-locked laser. It has shown that its single pulse selected probability is about 100%, the output unstability is better than ±5%.