The objective of this study is to investigate the field trial efficacy of imidacloprid 600 g/L flowable concentrate for seed coating（FSC） on Rhopalosiphum maidis. The results showed that the control effect was 72.38%～77.00%, with an increase of yield by 4.96%～10.50% by seed-dressing treatment with 400～600 g/100 kg FSC, and there was no significant difference from Thiamethoxam 30% FSC（P＜0.05）. Both Imidacloprid 600 g/L FSC and Thiamethoxam 30% FSC had meaningful control efficacy against R. maidis. The results of field experiments showed that Imidacloprid 600 g/L FSC was long persistent, convenient, less cost and did not affect ecological environment when it was applied to control R. maidis.