Ultrasonic guided wave detection has gradually become one of the effective methods for weld defect detection due to its characteristics of high detection efficiency and long detection distance. At present, the signal excitation source of ultrasonic guided wave detection in domestic usually combines signal generator and power amplifier, which is not convenient to operate and the latter is expensive and has limited performance. In order to surmount its shortcomings, an ultrasonic guided wave detection broadband excitation source based on FPGA is designed. The excitation frequency and pulse cycle number of the excitation source can be flexibly adjustable according to different detection objects. The power amplifier of the excitation source can achieve an output amplitude of 100 Vpp in the excitation frequency range of 250 kHz~4.5 MHz on a 50 Ω load, and the piezoelectric transducer can be directly driven. Verilog language is used to design the driver of each hardware and the serial communication protocol with the host computer. The test has verified that the excitation source can achieve defect detection with the receiving and acquisition module on a 500 mm long wield. The module is small in size, reliable in performance, and has certain practical value.