In this paper, we describe a new method for fast direct classification and counting of the surf ce defects in optical disks and substrates, and present the correspounding experimental results of the surface performance evaluation by this method. Defect signals are obtained with an auto- focusing laser beam scanning the surface of optical disk or substrate, and they are directly classified and counted by the electronic circuits. The number of all kinds of defects and the size are transfered into the micro-computer, then the defect density of optical disk or substrate are calculated by the measuring software, so that the surface performances of optical disks or substrates are effectively evaluated.