Abstarct: Nowadays due to the economical and biological reasons there are restrictions on consumption of energy. According to this fact, recycling and reusing energies that are left in the environment without any use is becoming more and more important on day to day basis. Among all, Internal Combustion Motors are of a great importance and also utilizing their outlet heat is important too. We can recycle the significant amount of wasted energy in motors’ outlet by using organic Rankine cycle. The low temperature of our desired heat source is why the organic type of Rankine cycle is used. Which causes better performance in organic fluid compared to the water. In this research, we first introduced the proper working fluid for utilizing in this cycle by investigating and considering different parameters in it. Then we analyzed the effect of each parameter on thermodynamic performace like work production and efficiency. Results show that using toluene and R245fa fluids as a working fluid in order to optimize the recycling of wasted heat in two low temperature and high temperature sections are proper. Utilizing these two fluids resulted in 24/8% efficiency in recycling cycle.