A method is disclosed for generating a sub-nanosecond pulse laser, using a voltage-increased type electro-optical Q-switched laser. The method includes: applying a square wave driving signal on a Pockels cell in an electro-optical Q-switched laser by using a Q-switch driver module, where the peak voltage of the square wave driving signal is higher than the quarter-wave voltage of the Pockels cell; and performing, by controlling the loss related to the electro-optical Q switch with a voltage of the driving signal increasing from 0 to the peak voltage, a change of the working state of the electro-optical Q switch from a switched-off state to a switched-on state, and then to a partially-switched-on state. The intracavity laser is exhausted within a quite short time, so that the pulse width of the laser is shortened, to implement sub-nanosecond operation of a pulse laser.