Abstract: The study aims to investigate the best spraying dosage in flax field and the residual amount in linseed of 108 g/L haloxyfop-R-methyl EC and 10% quizalofop-p-ethyl EC. An experiment was conducted to clarify the control effects of two herbicides on Gramineae weeds in flax field and determine herbicides’residue in linseed by stem and leaf treatment, GC-MS and HPLC-MS/MS. The results showed that the two herbicides were safe and had good control effect on Gramineae weeds in flax field, and could increase the flax yield significantly. Their plant control effects were 94.34% and 93.34% , the fresh weight control effects were 95.26% and 94.85%, and the yield-increase rates of the flax were 92.50% and 91.48% when effective dosage of the two herbicides were 145.8 g/hm2 and 90 g/hm2, respectively. Residual contents of herbicides were in accordance with the maximum residue limits of edible vegetable oil, the residue amount of the two herbicides were 0.10 mg/kg and 0 mg/kg in linseed respectively.