Most studies related to determining the expression profile of genes and specific promoters used histochemical localization of the reporter gene, gusA. While the histochemical method for visualizing gusA expression suffers from several limitations in the determination of gene expression and location, especially in the tissues with high background acitivty. To solve this problem, a transient expession vector pBI221-RFP/GFP, was constructed using GFP and RFP as double fluorescent marker genes. This vector used CaMV 35S promoter to drive GFP and determine the transforming efficiency. It analyzed expression profile of the target gene and promoter through the RFP activities of the tranformed tissues. Through the specific promoter AGPL1 from watermelon and E8 promoter from tomato, it is resistible to use this vector to study the expression patterns of promoters. Results indicated that the pBI221-RFP/GFP is a very efficient transient expression vector that can be verify the functions of the genes and promoters.