Abstract: In order to optimize the process parameters for slicing sapphire wafer through multi-wire sawing with diamond wire saw, the diamond wire samples of the different stages are obtained by machining tests.The surface morphology of these samples are observed through scanning electron microscopy, while the tensile ultimate load of the samples are tested by tensile testing machine and the fracture morphology is analyzed.The experimental results show that the diamond particles in the life cycle experience the process of cladding worn, baring, cracking and falling off.The diamond particle cracking is the main cause of falling.During life cycle, the tensile limit of the wire does not decrease with wire wear and falling of diamond particles.Furthermore, the fracture image of fracture test samples are divided into three zones:the crack propagation zone, transient breaking zone and the plating zone.The separating can be observed between the plating zone and the steel wire.On the basis of the analysis results, the optimization method of process parameter is given.