In recent years, studies on cellular behavior have been developed to diagnose and treat various diseases, including cancer. In this regard, the use of microfluidic systems for this purpose has been much considered. Microfluidic technology is one of the new technologies that has been able to take advantage of the special properties of micro and Nano-sized fluids in the fields of research, biology and medicine. A microfluidic device is a design of channels of silicon, PDMS or glass that the liquid can flow in them. In this study, the existing methods were investigated for particle separation by using the features of microfluidic systems to design a system for the isolation of circulating cancer cells. The main physics used in this system is the use of inertial forces for cell separation. In this design, we have tried to optimize the existing designs by integrating other methods to this way. Using simulation in Comsol software, the flow parameters including pressure and velocity were investigated. By studying the different methods of producing of microfluidic systems, soft lithography method was choosed and a prototype design was fabricated. Experimental tests were performed using breast and skin cancer cells which presented a 40-50 percent tumor cell separation efficiency. Keywords: Cancer, Microfluidic, Circulating tumor cells, Skin cancer, Breast cancer, Soft lithography, PDMS