Due to the laborious and scale-up limitation we have developed a simple system named "root absorption" to express foreign proteins in plants successfully. It has been shown that GFP was expressed in tobacco plants by root absorbing the Agrobacterium suspension containing TMV-based P35S-30B-GFP vector. Various factors influencing the gene expression were studied including Agrobacterium cell density, seedling age, plant materials and inoculation conditions. This system has the special advantages as simple and convenient work process, ease to scale-up and higher level of expression than leaf infiltration. Interestingly, GFP was expressed at 24h post-absorption. We assume that the root absorption system will facilitate the large-scale production of the recombinant pharmaceutical proteins in plants by means of transient expression.