Fixed abrasive technology which has many advantages is one of the future machining directions. Free and fixed abrasive lapping of BK7 glass was investigated and different material removal modes and surface damage categories by lapping were discussed. The results show that material removal rate is larger for free abrasive lapping than that of fixed abrasive lapping with four abrasive sizes and decreases with diamond size decreasing in two lapping processes. Surface quality is better for fixed abrasive lapping than that of free abrasive lapping at the same diamond size and gets better with the decreasing of diamond size. Fixed abrasive lapping can achieve simultaneously high MRR and good surface quality.