At present most of the Marx generator based on semiconductor switches not only need generate the same number of trigger signals as the number of switches, but also consider the isolation from output high voltage and driving the signal processing, which makes Marx generator have complex circuits, large volume. In this paper, a new type of Marx generator based on semiconductor switches is designed. This generator need only one trigger signal which is generated by an avalanche transistor, other switches are triggered by the signals which are generated by voltage dividing capacitive. In the PSPICE, a five-stage Marx generator is designed. Choosing a 400V DC voltage source charged, pulse voltage with 1.9KV amplitude and 100ns pulse width is obtained. Finally, a fourstage Marx generator is designed. The charging voltage is 200V and the pulse width of trigger signal is 500ns. A pulse voltage with amplitude 736V and pulse width 562ns is obtained.