The invention provides a multi-frequency RFID reader based on software radio. Due to lack of a uniform standard, the radio frequency recognition frequencies of all countries are not consistent, and in order to adapt to the requirements of different countries, a reader-writer is required to have an RFID product which has the requirement of recognizing multiple frequencies to serve for different countries or districts. The invention provides the multi-frequency RFID reader based on software radio. The multi-frequency RFID reader is formed by a radio frequency module, a baseband module and a power module, wherein the power module is respectively connected with the radio frequency module and the baseband module; the radio frequency module is used for realizing modulation and demodulation on a baseband signal and transmitting or receiving a modulated signal; the baseband module realizes control, encoding, decoding and inspection of the whole reader-writer, interaction of the reader-writer and an upper computer, and control on the radio frequency module; and the baseband module comprises an ARM processor system and a programmable logic, the ARM processor system is connected with the programmable logic and the programmable logic is connected with the radio frequency module.