[Objectives]  To study the function of the C002 salivary protein gene in the aphid Sitobion avenae (F.). [Methods]  A C002 gene was cloned based on the C002 gene of A. pisum. Real-time quantitative PCR and RNAi experiments were then conducted to explore the expression patterns and the function of this gene. [Results]  Bioinformatics analysis shows that the cloned sequence contained a 663 bp open reading frame encoding a protein of 220 amino acid residues. It was therefore named SaC002. Transcripts of SaC002 were detected in all stages of S. avenae, and its expression reached the highest level in 2nd instar nymphs. RNAi analysis revealed that S. avenae fed with dsC002 were disturbed, and that the expression levels of C002 decreased by 54% and 69% after continuous feeding for 4 d and 6 d, respectively; significantly lower than in the control group (P<0.01). Larval survival rates decreased by 32.2% and 53.3% compared to the control group after continuous feeding for 4 d and 6 d. When S. avenae were fed aphid-susceptible wheat (Beijing837) after feeding on dsC002 for 4 d, its survival rate decreased rapidly within a short time. On day 6 and 8, the survival rate dropped to 44.4% and 35.6%, respectively, significantly lower than that of the control group. [Conclusion]  The results indicate that silencing the C002 gene can be lethal to aphids feeding on specific host plants. SaC002 may serve as a potential target gene for controlling S. avenae.