138 rice (Oryza sativa) germplasms were identified to study the allelopathy to barnyardgrass (Echinochloa crusgalli), using the relay seeding technique. The results showed that Qingkun 2 from Jiangxi Province, Xiayitiao from Jiangsu Province, Jizaoxian from Anhui Province, Ganzaoxian 37 from Jiangxi Province, Shangnuo 1, IR68465-2-3-2 from IRRI, and Shuiyuan 2 from Korea had a strongly excellent inhibition effect on barnyardgrass. Results from pot culture showed that Gumei 2 and Zhong 156 had a greater inhibitory effect than control, and allelopathic material TN1 had no significantly inhibition effect, compared to non-allelopathic material Xiushui 63. The effect of Zhong 156 was related to its plant height, and significant different from that of Xiushui 63. Gumei 2 had a stronger inhibition effect on barnyardgrass, due to its own allelopathic trait.