An idea that using fuzzy immune PID to regulate the density of the starch production-line was put forward after the analysis and comparison of the principle of tradition PID, Smith prediction PID and fuzzy immune PID. A mathe matical model of one of density loop of starch productionline was built to design and simulate these three controllers. The simulation results show that the fuzzy immune PID is better than tradition PID on the hand of control effect and its robustness is higher than Smith prediction PID. DDE protocol and ActiveX of Matlab were adopted to realize data exchange with RSView32 of the starch production-line and transmit the algorithm of fuzzy immune PID to RSView32.