Abstract: The Microstructure of Bi brass with different content of silicon was observed by PHILIPS -XL30 scanning electron microscopy (SEM). The mechanical properties of samples were tested by HY-1080 electronic tensile testing machine. The cutting performance of the alloy was detected by C6136 horizontal lathe. The results show that the proportion of β phase in bismuth brass increases with the addition of silicon and the proportion of α phase decreases. The elongation and shrinkage ratio of cross section of bismuth brass decreases with the increasing silicon content, while the tensile strength increases. The cutting performance of bismuth brass is improved with the increasing silicon content..