The direct detection of the earth-similar planets nearby bright stars needs high-contrast imaging. We proposed a nulling coronagraph that can, in principle, totally cancel the on-axis point-source starlight for broadband high-contrast imaging. The nulling coronagraph also features close angular distance imaging and high throughput. Equipped with a telescope with only 1.5-m aperture size, it has the potentiality to be able to resolving and directly detecting earth-similar planets at 0.1" (1 λ/D) close-distance in the visible wavelength range. The requirement for a small telescope is a significant advantage for future space missions. We discuss the working principle, instrument realization, error and sensitivity analysis, and the estimated performance of the nulling coronagraph.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.