Abstract: Our aim in this study is to obtain an effective plant expressing system for exogenous proteins by investigating the stability and accumulation of exogenous protein expressed in plant. Optimized exogenous proteins expressing system in plant is achieved via co-expression of silencing inhibitors, application of organelles localization signal and silencing of atg5. The results show that silencing suppressors p25 or HC-Pro of plant virus promoted exogenous protein accumulation by inhibiting mRNA silencing. Localization signal of endoplasmic reticulum (ER) enhanced exogenous protein yield. The silence of atg5, one of the key genes of autophagy pathway, increased the accumulation of exogenous protein by suppressing the degradation of exogenous protein. In view of the exogenous protein which is easy to be degraded, ER localization signal combined with silencing inhibitor or autophagy-deficient plants can be used as a new strategy to improve the expression and stability of exogenous proteins.