High chromium alloy is a kind of metal material with high corrosion resistance and high hardness. It is used in the thrust bearing bush of nuclear main pump in a severe environment. Based on the content of elements in high chromium alloy and the manufacturing preparation process of the alloy, a method for constructing the molecular dynamics (MD) model was proposed to study the machinability of the alloy. The MD simulation model of high chromium alloy was established based on alloy structure with the atomic random permutation and two bubble algorithms. Then, according to the actual manufacturing process of the high chromium alloy, a quenching process was introduced to simulate the actual manufacturing process of the high chromium alloy, so the property of the high chromium alloy model was improved and it was more suitable for precision machining. The accuracy of the model was verified by the internal structure and by calculating the nanohardness and density of the high chromium alloy model after adequate relaxation to studying the nanomachining performance. The coordination number of the high chromium alloy is about 4.3 calculated by integrating the radial distribution function. And there is not a perfect crystal structure in the alloy model. The density of the alloy model is about 7.549 g/cm₂, which agreed with the results of actual experimental measurement. A series of MD simulations were performed to investigate the nanomechanical property of the high chromium alloy by using the MD model. The maximum depth of 2 nm, 2.5 nm and 3 nm indentation simulations were carried out with 3 nm indenter. The results showed that the nanohardness is about 6.951 GPa-8.095 GPa, these properties are very close to the real measured results. The material and the deformation property of the high chromium alloy were stable during the indentation process.