Abstract: The new-style low heat-inertia fast-heating furnace for metal samples is controlled by PID algorithm to exert fast-heating and fast-cooling effects as well as circle control on rise-and-fall temperature on the samples. This system has been proved effective by experiment especially for sensitive adjustment to time and velocity, of which the temperature control theory and optimization design by PLC for system discrimination, PID (proportion-integral-differential) parameter setting etc. are presented.