The boron (B)-sulfur (S) co-doped single crystal diamond was prepared by diffusion device using high purity boron powder and sulfur powder at 1 300 ℃ under a high temperature vacuum. In this paper, scanning electron microscopy, X-ray energy spectroscopy, Raman spectroscopy, and other tests show that the morphology and crystal quality of diamond change with doping of the two elements. The co-doping diamond crystal surface morphology is complex, and the internal morphology of etch pits and gully is stepped. With the doping amount increases, the steps appear to fracture, and high content of boron and sulfur atoms is detected at the etch pits. The diamond with B-S mass fraction of 0.5 have the highest content of boron and sulfur atoms at the etch pits. With the impurity atoms infiltration, full width at half maximum of Raman increases, and crystal quality of the diamond decreases. Hall testing at room temperature reveals that the diamond resistivity decreases after doping. The samples with the B-S mass fraction of 1 and 2 exhibit p-type conductivity. While the sample with the B-S mass fraction of 0.5, the Hall coefficient is negative and shows n-type conductivity.