Small RNAs, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), play crucial roles in post-transcriptional gene silencing (PTGS) in eukaryotes. Small RNAs function cell-autonomously as well as non-cell-autonomously. It has been well characterized that pathogenic fungi secrete some effector molecules facilitating their infection into plants. However, it is unclear whether molecules produced in plant cells are able to move into fungal cells during infection. To test if small RNAs generated from plant cells can move to fungal cells during infection, we generated transgenic Arabidopsis and rice plants expressing siRNAs targeting GFP gene generated from double-stranded RNA interference (dsRNAi) constructs for GFP gene. And then these transgenic plants were inoculated with transgenic rice blast fungus, Magnaporthe oryzae, expressing GFP transgene. Here, we showed that ectopic expression of siRNAs targeting GFP gene in transgenic plants significantly suppressed GFP expression in rice blast fungi inoculated, indicating that small RNA molecules generated in plant cells can move into infected fungal cells and efficiently degrade fungal GFP transcripts. Our results would provide a new small RNA-based strategy for the development of resistant crops against fungal pathogens.