In order to precisely measure the surface topography of a diamond grinding wheel in a non-contact way, an interferometry based special topographic measurement system was established and the principle and key techniques of the system were investigated. On the basis of the principle of vertical scanning white light interferometry and the characteristics of measured objects, an approach suitable for grinding wheel measurement was presented. Then, the key techniques such as automatic scanning range determination, larger vertical scanning, three dimensional surface reconstruction and abrasive grain recognition, were analyzed. With a specific setup for wheel fixing, a wheel measurement system was given based on the proposed method and its stitching method for a larger area evaluation was analyzed experimentally. Experimental results indicate that the correlation coefficient of the regions before and after stitchings is more than 0.8 by using area-based method with an overlapping area of 30%-50%. The height error of the stitched area is less than 0.4 μm. The system recovers the three dimensional surface of the grinding wheel and obtained measuring ranges and accuracy meet the requirements for analysis and evaluation of grinding wheels.