Rice is one of the world's oldest and most important food crops, and it is the staple food of roughly half of the world's population. The cultivation of rice in Ethiopia is a recent phenomenon. Despite being a relatively new crop in Ethiopia, rice production is rising quickly. However, the post-harvest rice processing technique is exceedingly inefficient and had a low head rice yield. The impact of crop and threshing characteristics such as variety, grain moisture content, thresher speed, and peg spacing on milling quality was not investigated. Therefore, the main objective of this study was to investigate the effect of threshing factors on the milling quality of rice for selected cultivars. As test material, indigenous rice varieties, rice thresher, grain moisture tester, tachometer, lab scale rice husker, and miller machine were used. The experiment's tests were conducted successfully at the Fogera National Rice Research and Training Center. A factorial based on a randomized completely block design with three types of cultivars Shaga, Ediget, and Nerica-4, three levels of moisture content of 24%, 17.5%, and 11%, and three-level drum speeds of 740, 840, and 1100 rpm, and three levels peg spacing of 60, 70, and 80 mm were conducted in triplicates. The Duncan's test was used to compare treatment means at a 95% level of significance after the analysis of variance using R-Studio statistical software. The result revealed that the percentage of threshing breakage ranged from 0.34% to 14.49%, threshing hulling from 0.78% to 13.78%, husking breakage from 3.83% to 17.98%, husking efficiency from 94.48% to 72.79%, milling breakage from 5.47% to 24.17%, and head rice yield ranged from 64.06% to 45.87%. The head rice yield regression linear equation for Shaga, Nerica-4, and Ediget cultivars had a significant correlation coefficient of R 2 = 0.9618, R 2 = 0.9473, and R 2 = 0.9850, respectively. whereas thresher speed and peg spacing have a negative impact on head rice yield, whereas moisture content has a positive effect on head rice yield. In general, the highest head rice yield was obtained when the grain moisture content was 24%, the threshing peg spacing was set at 80 mm, the cultivar was the Shaga variety, and the drum speed was set at 740 rpm. As recommendation the effect of threshing factor and crop parameters on physical losses such as scattered loss, unthreshed grain, and cleaning efficiency for local cultivars is not investigated in this thesis work. Key words: Head rice yield, Grain breakage, Milling quality, Threshing, Hulling, Milling, Postharvest loss