In this work design of experiments have been used to optimize various control factors of a cold storage evaporator space inside the cold room or in the other words the heat absorb from the inside of the cold room by evaporator will be maximized. Taguchi orthogonal array have been used as a design of experiments. Three control factors with three levels of each have been chosen for analysis. In the evaporator space the heat absorbs by the evaporator and fins totally a convective heat transfer process. The control factors are Area of the evaporator with fin (A), temperature difference of the evaporator space (dT), and relative humidity inside the cold room (RH). Different amount of heat gains in the cold room for different set of test runs have been taken as the output parameter. The objective of this work is to find out the optimum setting of the control factors or design parameters so as the heat absorb in the cold room by the evaporator will be maximum. The Taguchi S/N ratio analysis have used as an optimization technique. Larger the better type S/N ratio have used for calculating the optimum level of control parameters, because it is a maximization problem. Analysis of variance ANOVA was also performed on the test results to find out the significant control factors.