Transition metal borides have been considered as potential superhard materials by researchers.  However, due to the low diffusivity of transition metal borides, it is difficult to synthesize pure phase bulk materials to obtain their hardness.  High temperature and high pressure method is an effective method to synthesize high quality transition metal borides. However, sometimes the synthesized samples are very easy to fracture by high temperature and high pressure method, and the hardness of the synthesized samples cannot be measured.  In this paper, pure phase WB was synthesized by high temperature and high pressure method.  The influence of synthesis temperature on polishing quality was analyzed.