Two different type of microdefects have been observed by means of Cu-decorating X-ray topography and etching method in p-type silicon single crystal grown along and/or n-type ones grown along direction. A kind of defects with special configuration has also been found in n-type silicon single crystal. The distribution and configuration of these defects are discussed preliminarily.It was the first time to investigate the "as grown" microdefects in silicon single crystal grown by Czochraski method directly by means of X-ray transmission projection and/or section topography. X-ray topographs of microdefects in CZ silicon crystal were obtained. The configuration, size and distribution of the microdefects observed were in agreement with that obtained by Cu-decorating X-ray topography quite well.