**Abstract:**
The control is the main process in industries in that liquid level control plays important role in many industries like petroleum, food manufacturing etc. Many process industries use conical tanks because it prevents the accumulation of solid at the bottom of the tank. The non-linearity and constantly changing cross section of the conical tank are the immense challenge in control in process industries and it cannot be controlled by the linear Proportional Integral Derivative (PID) controllers. The Proportional-Integral (PI) controller is commonly used to control the level in process industries. Tuning of the PI gain parameters is setting the proportional, integral constant to get the best control of the process. The standard controller tuning methods are the Ziegler Nichols (Z-N) and Cohen-Coon methods. Most of the industries using PID controller for controlling the process so the PID controller wants to tuned to get a better performance, for that optimal selection of PID controller using particle swarm optimization technique is used in this project and also the Z-N tuned PI controller, IMC controller are designed for the Conical Tank System (CTS) and simulated using MATLAB/SIMULINK environment. From the simulation results it has been proved that the optimal controller gives good control system performance than other controllers.

**Keywords:**
Conical tank, Piecewise Linearization, Optimal Controller.