Abstract: Distribution of the spherically weathered granite(commonly known as the boulder)has a direct impact on the construction of urban rail transit project. It has important practical significance to detect spatial distribution of boulder accurately. This paper explores the distribution of granite boulders during subway construction. It combines with an instance of geophysical testing for detecting the distribution of granite boulders at the site of Shenzhen Metro Line 11.The distribution of granite boulders between two wells was studied with cross-hole ultra-density resistivity imaging. Test results can distinguish the difference of resistance between boulder and surrounding soil. Test results and field-proven drilling show that the geophysical method is satisfactory in detecting the spatial distribution of granite boulders in a certain degree, which provides guidance for further targeted investigation of the subway project and rich detection means of granite boulders.