Cost of the diamond wire saw is the second only to SiC single crystal material itself when ultrasonic wire saw cutting of SiC wafer. The force model was established on the condition of ultrasonicassisted wire saw cutting. Theoretical analysis and related experiment of forces and failure forms of the diamond wire saw were done. The influence rules were studied on the feed speed of the workpiece to wire saw slanting angle, cutting way to wire saw wear, cutting fluid to wire saw wear and abrasive failure modes to the properties of wire saw cutting. The results show that the wire saw is easy to be pulled apart with the workpiece feed rate or the ultrasonic amplitude increasing. However, if it is too small, the cutting efficiency may be decreased. In order to improve efficiency by increasing the workpiece feed rate, it is a must to increase the strength of wire saw or roller diameter, or to reduce the wire saw speed. Wire saw wear is reduced about 40% when ultrasoundassisted cutting. The wire saw surface block is more serious when using Ecocool Resist EP microemulsion as compared with running water; and slight broken of diamond grits are benefit to cutting.