To explore the cutting mechanism of cortical bone material during abrasive water jet cutting and improve the quality of cutting surfaces in the abrasive jet cutting process， sodium chloride and garnet were used as abrasives to cut cortical bone. The changes in surface roughness under different cutting directions and the microscopic scratch characteristics were compared. The experimental findings demonstrate a characteristic pattern in which the roughness values of the cutting section initially decrease and then increase. Based on these roughness values， the section can be divided into three distinct regions： initial region， smooth region， and rough region. When using sodium chloride as the abrasive， the average roughness values of the cutting surface in the direction perpendicular to the bone unit are 1.74 times and 1.70 times those in the directions parallel and traverse to the bone unit， respectively. When using garnet as the abrasive， the average roughness values of the cutting surface in the direction perpendicular to the bone unit are 1.41 times and 1.55 times those in the directions parallel and traverse to the bone unit， respectively. Numerous micrometer-scale scratches are formed on the cutting surface during the cutting process. The impact of sodium chloride and garnet abrasives on the scratch characteristics of the cutting surface was compared. Compared with garnet， when using sodium chloride as the abrasive， the dimensions of the cortical bone cutting surface scratches are too large， with similar length and width values； the range of scratch depth values is greater.