To screen for high-efficacy herbicides controlling the invasive weed Saccharum arundinaceum， the herbicidal activities of hexazinone and glyphosate against S. arundinaceum were evaluated under both laboratory and field conditions， and the combined effects of their mixture were investigated. The results showed that treatment with 5% hexazinone granules （3 375 g/hm2） resulted in chlorosis in S. arundinaceum by 30 days after treatment （DAT）， complete plant death by 60 DAT， and no regrowth at 120 DAT. 41% glyphosate isopropylamine salt AS（2 306.25 g/hm2） induced rapid yellowing by 14 DAT， but was followed by regrowth by 60 DAT.The synergistic mixture of hexazinone （562.5 g/hm2） and glyphosate isopropylamine salt （384.375 g/hm2） achieved the control efficacy of 100%， completely eradicating S.arundinaceum. It is indicated that the mixed formulation of hexazinone （562.5 g/hm2） and glyphosate isopropylamine salt （384.375 g/hm2） has excellent control efficacy against S.arundinaceum.