food security and health is one of the most important issues of human life.Cowpea Vigna unguiculata (Willd) is an important grains that cultivated in wide area in the world and consume as a food sources. Twospotted spider mite . Tetranychus urtica )Koch ( is one of the most important pests of cowpea. One of the most important measures to increase the effect or optimize the use of acaricides is to use them at appropriate dosage and in appropriate temperature and relative humidity conditions. The Response surface method is a set of mathematical and statistical methods used for modeling and analyzing issues in which the desired response is influenced by several independent variables The purpose of applying this method is to find out the best set of levels of variables. This study was carried out to investigate the effect of independent variables on the output variables of the experiments. As an approximate model is obtained, it was tested by the fitting goodness method. In this research, in order to optimize the use of acaricide propargite with the aim of maximizing the mortality rate, the input process variables were studied by library studies, temperature 25-30 ° C and humidity 55-65% and acaricide dose 900 -2300 μl per 1000 cc distilled water and output variable is the percentage of mortality in adult female mites . For this purpose, the central composite design with 3 factors in 5 levels and 6 replications in the central point was used to estimate the error of the experiment. The results of analysis of the data prove the significance of the quadratic model 2FI (P >0.0001), and the ratio of actual correlation coefficient and adjusted correlation coefficient is 0.6443 and 0.4802, which indicates that the fitted model has a good description of the data dispersion and shows the relative effects of temperature and relative humidity on the mortality rate of adult female mites. To conduct the experiments and determine the optimal point, the numerical optimization method of the Design experts software 7.00 was used. The ideal optimum for propagitis acaricide was determined in temperature of 26.01 ° C, humidity 57.03%, and a dose of 1183.87 μl per 1,000 cc distilled water with a satisfaction of 97%.