We propose a high-contrast coronagraph based on the step transmission filters for the direct imaging of an Earth-like exoplanets. To demonstrate the performance of the coronagraph, two 50-step transmission filters were manufactured and several experiments have been performed. At present, the coronagraph can reach a high contrast around 10^-7at an inner angular distance of ~2λ/D in the visible wavelength. Such a coronagraph should be installed on an off-axis space telescope which will be promising for the direct imaging of an Earth-like exoplanet in the future.