Abstract: To investigate the deterrent effects of 75% ethanol extracts of three plants (Humulus scandens, Duranta repens and Nicotiana tabacum) on adults of Phyllotreta striolata (F.), a deterrence effect model for the mixed plant extracts was established by adopting orthogonal rotational regression combination design, and the relationships between different factors were analyzed. The results showed that after tobacco feeding, the mixture of Nicotiana tabacum extract and Duranta repens extract had a synergistic deterrent effect on adults of Phyllotreta striolata (F.). However, the mixture of Humulus scandens and Duranta repens extracts or Nicotiana tabacum extracts had an antagonistic interaction on the deterrent effect. Therefore, the mixed ethanol extracts of Duranta repens and Nicotiana tabacum were recommended to deter adults of Phyllotreta striolata (F.) and to reduce their damage to Nicotiana tabacum.