Flour extraction was analyzed by milling different varieties of wheat with different gaps of break rolls of Buhler automatic laboratory mill MLU-202. Straight flour extraction increased with decrease in the roll gap, which was mainly due to increase in break-related flour extraction, especially the flour from the first break roll. Farina extraction also increased with decrease in the roll gap, which contained a large amount of shorts and relatively small amount of flour. Straight flour extraction of wheat with larger kernel diameter was higher, but their correlation was not significant. Meanwhile, the kernel hardness showed significant (-) correlation with the flour extraction and (+) correlation with the shorts extraction. Consequently, the effect of the break roll gap was significant on the flour extraction, and the kernel hardness influenced the flour extraction more than the kernel diameter.