According to the electro acoustic pulse method for space charge measurement system of high voltage pulse power supply, the paper presents the pulse forming line and the oscillating circuit principle to realize the ultra narrow pulse high voltage. In this paper, based on the detailed discussion and analysis of the influence of the parameters of the pulse generating principle and the forming line, the ultra narrow high voltage pulse power supply is fabricated and tested. The results of the test can be seen that the high-voltage pulse generator based on the principle of pulse forming line can form a stable ultra narrow high voltage pulse (ns class). With the pulse width of the pulse forming line length increases, and it can be applied to space charge measurement system of pulse electro acoustic method.