The need for high quality water significantly increased during the second half of the last century. It has been a complex task to develop an optimized process without actual testing which usually requires costly test procedures. The desalination industry is the life live for several countries and zones around the world, especially the countries around the Persian Gulf such as Iran. Expansion in desalination industry is associated with reduction in the power consumption and increase GOR value. For this reason, a general computer code for MED-TVC type of desalination has been developed and is currently used by only MED-TVC Manufacturer Company in Iran (Fan-Niroo Co). The present work shows parametric optimization method to increase GOR value of MED-TVC systems with consideration of influence of all factors. This program provides engineers a cost effective tools for designing, developing and optimizing the thermal desalination plants. It is the objectives of this work to develop a mathematical model which predicts the influence of all factors on heat transfer coefficients, temperature and pressure, total capacity and performance ratio of the system under design and operating conditions. The validated model is further used to test the effect of variations in certain parameters in the process in order to investigate their influence on total capacity in the plant. By means of parametric study, the computer simulation tool developed will help designers to achieve the best setting for desalination process to minimize the energy consumption. In order to validation of program outputs, the optimization results of this program tested on an available MED system in Kish Island and this optimization lead to increase the product and GOR value of this system. So it is concluded that this experience well proves program validity in order to design and optimization of MED-TVC systems.