Flow regime recognition of two-phase flow is of great importance in industrial process. This paper describes the role of the field-programmable gate array (FPGA) hardware, in the implementation of electrical resistance tomography (ERT), which is used to analyze gas/liquid two phase flows. Firstly, a brief introduction and some theoretical analysis are made about the basic principles of Direct Digital Synthesizer (DDS). Then a signal source for ERT system based on DDS and FPGA is designed and a kind of compression ROM is realized. The whole system has been simulated in the Quartus II 7.2 simulation environment and successfully downloaded to the chip of the Cyclone II EP2C5F256C6. The operating results and the theoretical results show that the proposed method can greatly improve the developing efficiency, save plenty of the system resources and improve the reliability and flexibility.