Abstarct: Abstract Pulsating heat pipes are a heat transfer tool with a complex function, where several thermodynamic parameters affect their thermal performance. In this research, using the design of experiments with the help of design-expert software and the response surface method, the experimental study of the performance of the pulsating heat pipe under the influence of the thermal power parameters, the filling ratio and the length ratio of the evaporator to the condenser in 5 levels has been studied. The pulsating heat pipe under study consists of 4 rounds of copper pipe with inner and outer diameters of 2.4 and 3 mm, respectively, and the overall dimensions are 3 × 200 × 210 mm. The main goal of this research is to reduce the thermal resistance under the influence of the 3 studied parameters, looking at improving the performance of the fluctuating heat pipe. By using the response level method, in addition to determining the optimal levels of each of the factors, the 2nd degree relationship between the factors and thermal resistance has been obtained. The thermal resistance changes according to the filling ratio parameters and the length ratio of the evaporator to the condenser have a turning point. The process of these changes will be direct before the turning point and reverse afterwards. The process of thermal resistance changes will always be direct in terms of thermal resistance changes; The slope of these changes decreases from a certain point until the drying phenomenon is reached. The lowest and highest amount of thermal resistance occurs in thermal power, filling ratio and length ratio equal to (3.109w,61.14%, 04.1) and (75.070%, 90w), respectively.