Transformation of silica complex melting process to its data information establishes a reliable timing rule for the high temperature melting process, and is of great significance for improving the direct fiber forming technology of blast furnace slag. Firstly, hierarchical clustering algorithm is used to detect the edge of gray image. The region growing and morphological processing are used to segment the image, so as to determine the position coordinates of the silica particle’s center of mass and draw the motion track. Secondly, the area and the generalized radius are selected as the indexes of edge contour feature. The experimental results show that the relationship between the area, generalized radius and time of silica and the fitting degree of quadratic curve is the highest. The above two indexes can be used to represent the melting process of silica and to estimate the actual melting rate of silica.