Abstract: Aiming at anti-disturbance characteristics of 4~20 mA current loop, and ability of real-time signal processing and complicated algorithm processing of DSP, and DSP’s abundant on-chip external devices and characteristics of I/O interface, the paper presented a kind of design scheme of 4~20 mA current loop based on DSP, and introduced basic composition of this current loop, application of DSP and control strategy of PID. It also gave a design example of 4~20 mA current loop based on DSP.