The proposed approach presents a design and implementation method for a software-defined broadband signal acquisition and playback system based on SoC, aiming to enhance the simplicity and flexibility of the system. By employing direct RF sampling technology, high-speed signal acquisition and playback are achieved, while digital signal processing technology enables more flexible programmable down conversion and signal processing in the digital domain. This system offers secondary development capabilities for software radio, addressing the issues of complex design and limited flexibility associated with traditional wideband signal acquisition systems that utilize superheterodyne IF sampling. Experimental results demonstrate that this signal acquisition and playback system supports an input/output frequency range of 1 MHz to 4 GHz, with a minimum signal bandwidth of 80 MHz. The sampling clock frequency is not less than 200 MHz. Moreover, the output power range for playback signals spans from -90 dBm to 0 dBm, with adjustable power levels in increments of 1 dB. Overall, this system exhibits exceptional flexibility.