In order to do an economic study and measure the productivity of the factors of production of the coldwater fish in Kermanshah province, all of the active farms of this province in 2015 agricultural year have been chosen as the statistical population. A part of the required data for this study is taken from the published official statics, and another part is collected through interviews via questionnaires with fish farmers and the experts of the fishery department of Kermanshah. Then using Eviews software and with the ordinary least square (OLS) method, the production functions have been estimated; and through the priority model test, Cobb-Douglas production function was finally chosen. Results show that the variables of the geographic location, education, the number of the released juvenile fish, the number of juvenile fish losses and using the aeration devices have a significant effect on the amount of the production (p<0.05). The sum of the coefficients of independent variables in the estimated production function is around 0.08, which indicates decreasing (downward) returns to scale. The production elasticity of aeration devices and water-returning pumps is more than the other inputs, suggesting that this input should be used more appropriately for this economic activity. Also the coefficient of the number of juvenile fish is 0.69, which indicates that if the number of juvenile fish is increased one percent, the production of fish will increase by 0.69 percent; and the demand for more released fish shows the direction toward the optimal production.In this study, results have indicated that the experience of the farm manager has no significant impact on the production (p>0.05), but education has a significant and positive effect (p<0.05). Expressing that technological level in this activity is high. Since this industry is a new activity in this non-coastal province, Kermanshah, so it seems logical that the educational level of employers would have a significant effect on the production.The comparision of the production function and the lnTFP functions indicates that some of the factors of production, which had a significant effect on the production function, have no significant effect on the productivity, and vice versa. Hence, this leads us to the point that to achieve a greater profitability and an optimal utilization of the factors of production, the estimation of the production function is necessary, but not sufficient; rather for a more accurate assessment of using the factors of production, in addition to estimating the production function, calculating the productivity indexes and estimating TFP function is demanded, so that a more complete study is provided.