A dual-band rectenna for radio frequency (RF) energy harvesting was proposed in view of the problem of low conversion efficiency of traditional dual-band rectenna. The rectenna is mainly composed of receiving antenna, an impedance matching circuit, a double voltage rectifier and a load circuit. Based on the miniaturized dual-band antenna, a new dual-band impedance matching network was introduced to improve the RF-DC conversion efficiency of the rectifier at a lower input power. In addition, the new impedance matching network reduces the complexity of the rectifier. Compared with traditional dual-band rectenna, the novel dual-band rectenna has higher RF-DC conversion efficiency in indoor environment for an incident power of -10dBm. The experimental results show that the RF-DC conversion efficiency reach 65.34% and 54.3% in 1.75GHz GSM band and 2.45GHz WLAN band, respectively. And the rectenna can be used in Internet of Things (IoT) low power devices.