The soft x-ray time-resolved spectroscopy is composed of a soft x-ray spectroscopic head and a soft x-ray streak camera. Because the soft x-ray spectroscopic head possesses a spectral resolution of 0.1 angstrom, the performances of the whole system mainly depend on the characteristics of the soft x-ray streak camera. In this paper, therefore, the design features and characterization of the soft x-ray streak camera are mainly described. In order to record the spectrum ranging from 30 angstroms to 230 angstroms on a limited photocathode slit length, the whole camera including the photocathode can be shifted along the spectrum without dismantling the camera from the soft x-ray generating chamber. The soft x-ray streak image tube possesses a specially designed vacuum-tight valve, which could be closed or opened in the vacuum chamber operated by a step motor, to prevent the photocathode sensitive to soft x- ray and internal intensified microchannel plate from pollution by water vapor or dust in the atmosphere. In order to test its dynamic performances, a soft x-ray diode was developed. The dynamic testing shows that the temporal resolution of this camera is 5 ps, which is limited by our soft x-ray source, dynamic spatial resolution is 20 lp/mm which implies the spectral resolution of 0.25 angstroms. Because of using CsI or KI photocathode deposited on a 1000 angstrom thick parylence film, the spectral responses range is approximately 0.05 to 10 KeV.