Abstract: This paper describes PID Controller tuning based on Particle Swarm Optimization in the Reverse Osmosis application. Particle Swarm Optimization is powerful method for tuning PID controller comparison to other conventional optimization techniques. It has some advance features such as easy implementation, stable characteristics; self-tuning, flexible design In this paper a model has presented that focus on the PH and Conductivity control in the Reverse Osmosis (RO). PSO algorithm is presented to tune the parameters of PID controller used in the RO Model. Computer Simulation in terms of a virtual process is designed to check the algorithm and compare the results with other optimization techniques.