Abstract: Red muds are highly alkaline residuces，their disposal and reclamation，have been a worldwide challenge due to lack of basic research. By comparing growth and physiological indicator of the Hybrid Giant Napier grass（HGN） and Zea mays（ZM）under different alkali stress，the adaptability of HGN and possible mechanism of alkaline tolerance in HGN and Zm had been investigated. It showed that the soil pH value could reduce after planting. Especially，the soil pH decreased from 9.49 to 9.49 about 60 days after planting. HGN had stronger tolerance to alkaline. The results showed HGN had a stronger vitality in the alkaline soil，and the growth characteristics，growth rate and yield of HGN were significantly higher than ZM. Otherwise，the yield of HGN were higher than ZM up to 50%. Our results showed HGN had a higher capacity to synthesize praline and soluble sugar than Zm，both of which were effective alkaline to leance indices，2 days after planting. Therefore，HGN is one of the most promising red muds phytoremediation plants that have a faster growth rate under alkaline stress condition.