The invention discloses a device and a method for transiently enhancing the digital video image. The device comprises a signal generation module, a coefficient adjustment module, a multiplication module, an addition module and an amplitude limiting module, wherein, the signal generation module and the coefficient adjustment module are respectively input at the same time through the original signal; the output signal is multiplied with a signal gained in the multiplication module and then generates an overlapped crispening signal; and the signal is summarized with the original signal in the addition module and then is output after the amplitude limiting by the amplitude limiting module. The method comprises the following steps: the image edge in the original signal generates a crispening signal; whether the high-frequency part of the original signal generates a gain adjustment coefficient or not is judged; the results generated by the two steps above after the gain multiplication is summarized with the original signal to obtain the corrected value; and the corrected value is output after amplitude limiting. The high-frequency signal cannot blink and the edge deformation cannot occur when the effect of the low-frequency signal is obviously enhanced, so that the image is more brilliant.