A method for online prediction of performance of sea water desalination equipment based on RO (Reverse Osmosis) is developed. The method comprises (i) a mathematical model of an RO unit, (ii) online estimation of membrane physical parameters of a nonlinear mathematical model representing the RO unit, (iii) analysis about time of estimated membrane transportation parameters, and (iv) analysis based on these estimated parameters, wherein an equipment operator can clean a membrane to restore the performance of the sea water desalination equipment based on the RO. The method is implemented in a computer-based control system for acquiring data and controlling the sea water desalination equipment based on the RO. The method helps to maintain the performance of the sea water desalination equipment based on the RO at an expected level, and prolongs the service life of the membrane without influencing the quality of generated osmotic water.