Wheat is one of the most important crops in Iran and its annual production is about 14 million tons per year, a significant amount of this product is wasted during harvest by the combine. One way to prevent losses is to choose the right combine harvesters and control their fall. In this study, two common types of combine harvesters, Jandir 955 and Jandirkah 955, were examined at 12 and 19% humidity. The losses of different parts, including natural losses, harvest platform losses, end combine losses and grain fracture rate in the tank were measured. In this study, SPSS23 software was used to analyze the data and the results of the study of the effect of independent variables on the performance dependent variable showed that the separate effects of these variables and the two-by-two and simultaneous effects of all three were significant.pay attention to this issue.