The invention relates to a small-size integrated steep pulse generating device. The small-size integrated steep pulse generating device comprises an oil tank and an oil-immersed impulse voltage generator which is hung inside the oil tank through an insulation support. The oil-immersed impulse voltage generator comprises an impulse voltage generating circuit based on a plurality of pulse capacitors, a plurality of gas spark switches and a plurality of resistors; a plurality of ring-shaped capacitor shielding structures, a first insulator, a second insulator and a third insulator, wherein the plurality of pulse capacitors and the plurality of gas spark switches are fixedly arranged on the second insulator in an alternate mode; the plurality of ring-shaped capacitor shielding structures are distributed around the plurality of pulse capacitors and fixed onto the first insulator; the plurality of resistors are fixed onto the front surface and the back surface of the third insulator; the plurality of resistors, the plurality of capacitors and the plurality of gas spark switches are electrically connected through high-voltage wires; the third insulator is fixed onto the second insulator; and the insulation support is connected with the first insulator. The small-size integrated steep pulse generating device can output expected pulses for testing large-volume test objects.