Abstract: The bacteria were screened from the rhizosphere soil of allelopathic rice PI312777 for weed suppression, which could provide a scientific basis for the development of herbicides source. The plate dilution method was used to isolate microorganisms, and a laboratory bioassay and a soil pot test with lettuce and barnyard grass were used as the receptors to evaluate the bioactivity of culture filtrate of the candidate strains. Laboratory bioassay proved that fermentation broths of two candidate strains Z1 and Z2 had the strongest inhibition on lettuce growth. And the maximum inhibitory rates of the fermentation broths on root length and plant height of barnyard grass were about 50%- 60% and 40%- 50% , respectively. In soil pot test, the inhibitory rates of the fermentation broths Z1 and Z2 were 28.1% and 27.0%, respectively on root length of barnyard grass, and 8.85% and 4.48%, respectively on plant height of barnyard grass. The fermentation broths had stimulative effect on root length of 3 rice accessions and no negative effect or little inhibition (inhibitory rate of 3% ). These results showed that rice allelopathy was correlated to their microorganisms of the rhizosphere soil and suggested that screening bacteria herbicides from the rhizosphere soils of allelopathic rice accessions would be a feasible approach.