Abstarct: Acoustofluidics, the integration of acoustics and microfluidics, is a rapidly growing research field that is addressing challenges in biology, medicine, chemistry, engineering, and physics. In particular, acoustofluidic separation of biological targets from complex fluids has proven to be a powerful tool due to the label-free, biocompatible, and contact-free nature of the technology. By carefully designing and tuning the applied acoustic field, cells and other bioparticles can be isolated with high yield, purity, and biocompatibility. Recent advances in acoustofluidics, such as the development of automated, point-of-care devices for isolating sub-micron bioparticles, address many of the limitations of conventional separation tools. More importantly, advances in the research lab are quickly being adopted to solve clinical problems. Separation of particle baxsed on their size in sample is one of the most important technologies in industrial production, chemistry and food industries, environmental assessment and biological research. The leading study was carried out with the aim of simulation and analysis of particle motion and how they were isolated in the presence of a surface acoustic wave. In the present study, the Helmholtz equation for the acoustic field and the linear piezoelectric equations are solved for mechanical motion and electric field. First, the acoustic wave and motion of particles in the acoustic field have been studied and then the order of separation of particles has been investigated. The results show that by increasing the diameter and density of the particles, the acoustophoretic force increases and they need more time to stabilize in the node or antinode.