Abstract: 【Objective】 To evaluate the control effect of pendimethalin EC, flumioxazin WP and their mixture to annual weeds and safety to cotton in the hope of providing scientific reference for chemical control to weeds in cotton field. 【Methods】 Plant control effect, fresh effect of 30 days and 40 days to annual weeds and safety to cotton after herbicides application were studied. 【Results】 The results showed that there were no difference of treatments on safety to cotton, and no significant difference on seedling emergence rate between each treatment and blank control. Plant control effects of 330 g/L pendimethalin EC(742.5 g/hm²)+50% flumioxazin WP(45 g/hm²)and 330 g/L pendimethalin EC(866.25 g/hm²)+50% flumioxazin WP(60 g/hm²)to annual weeds after 30 days were 96.52% and 97.91%, 95.86% and 96.48% after 45 days, fresh weight control effects were 92.89% and 94.44% after 45 days, respectively. The mixture of pendimethalin and flumioxazin had significant effect on annual gramineous and broad-leaved weeds in cotton fields. The plant and fresh weight control effects of 330 g/L pendimethalin EC 866.25-990 g/hm² to annual gramineous weeds were between 83.58% to 90.23%, and the effects of 50% flumioxazin WP 60-75 g/hm² were between 84.58% to 90.98%, no significant difference between them. The plant and fresh weight control effects of 330 g/L pendimethalin EC 866.25-990 g/hm² to annual broad-leaved weeds were between 82.62% to 88.90%, and the effects of 50% flumioxazin WP 60-75 g/hm² were between 85.06%to 92.21%. 【Conclusion】 The plant and fresh weight control effect of flumioxazin to annual broad-leaf weeds are higher than that of pendimethalin, which can be applied selectively according to difference dominant weeds population for reasonable controling weeds in cotton field.