The grinding mechanism of plunge belt grinding process with constant load is analyzed theoretically by using a statistical approach. The rate of effective grain cutting edge, the mean chip sectional area, the mean grain cutting area, the mean grain loading area, the grinding force, and the finished surface roughness are analyzed theoretically. The measurements of abrasive belt surface topography (grain cutting edge distribution, grain cutting edge density, and grain cutting edge half tip angle on the abrasive belt surface layer) are carried out by means of a scratching method. Further belt grinding experiments are carried out, and the experimental results for grinding force and finished surface roughness are compared with the theoretical values.