In this paper, the fall off and wear of electroplated endless diamond wire saws were studied when cutting granite. The self-made electroplating diamond wire saw was adapted in the experiment. Diamond particle size used was 200-230 US mesh. A kind of granite named Shi Daohong 375-2 with 18mm thickness was sawed. The test piece was sawed with constant cutting speed and feeding pressure. The topographies of wear, breakage and fall off of diamond grains were observed by using scanning electron microscopy. It was showed by the research that the damage of diamond grains appeared three forms including polishing wear and partial breakage and whole breakage. The fall off of diamond grain could be divided into two kinds of partial fall off and whole fall off during the cutting process. At the beginning cutting period, the wear of diamond grain mainly was polishing wear and partial breakage and with the extension of cutting time, the diamond grains would take place whole breakage and fall off.