A new and intelligent design method for PID controller with incomplete derivation is proposed based on the ant system algorithm (ASA). For a given control system with this kind of PID controller, a group of optimal PID controller parameters K~ , T[ , and T,~ can be obtained by taking the overshoot, settling time, and steady-state error of the system' s unit step response as the penComaance indexes and by use of our improved ant system algorithm. K 7 , T[, and T~ can be used in real-time control.This kind of controller is called the ASA-PID controller with incomplete derivation. To verify the performance of the ASA-PID controller, three different typical transfer functions were tested, and three existing typical tuning methods of PID controller parameters,including the Ziegler-Nichols method (ZN), the genetic algorithm (GA), and the simulated annealing (SA), were adopted for comparison. The simulation results showed that the ASA-PID controller can be used to control different objects and has better performance compared with the ZN-PID and GA-PID controllers, and comparable perfomaance compared with the SA-PID controller.