Due to the laborious and scale-up limitation we have developed a simple method named "seed absorption" to express foreign proteins in plants by means of transient expression. It has been shown that the reporter gene GFP was expressed successfully in tomato (Solanum lycopersicum L.) plants by seed absorbing Agrobacterium suspension containing TMV-based p35S-30B-GFP vector. Various factors influencing the gene expression were optimized including Agrobacterium cell density and other inoculation conditions. This method has the special advantages as simple work process, ease to scale-up, and further expanding the host range of plant bioreactor than previous methods. We assume that the seed absorption method will facilitate the industrial scale production of the recombinant pharmaceutical proteins in plants.