This study focuses on harvesting ambient radio frequency power and converting it to direct current for the terminal devices within Internet of Things or portable electronics such as equipping wireless devices.Villard voltage multiple circuit is the key component in the energy harvesting system.A 9-stage Villard voltage multiple circuit is designed and constructed,the calcula tion of efficiency of the circuit is shown in Formula(1).The circuit provides a 4.4 V output voltage without load at 2 cm with a radiated power of 6 dBm at 2.4 GHz.Voltage stabilized to 2.5 V by using LTC3456 chip with a 15 mA output current.The system used for test is shown in Figure 1,and in the fig urea calculator is also displayed which is energized with the harvesting sys tem.To record the voltage and current harvested with the circuit,an upper monitoring system is developed,in which the value of the voltage and current is displayed and saved by the upper monitoring in PC real time,the program designed on Visual C++ and the interface of the software is shown in Figure 2.Relations of converting energies with transmitted power are regressed with the recorded data,and its applications is demonstrated with a calculator being driven as depicted in Figure 1.