Vascular tissue serves as the channel for nutrient transport and signal transduction between different organs in plants. To study molecular identity and behavior of mobile substances transmitted between organs via vascular tissue, it is necessary to collect exudate from stem or other organs. Modified stem-cutting method for exudate collection in soybean was used in this study by selecting the optimum sampling time and position, using reagents preventing RNA degradation, etc. Diurnal dynamics analysis of exudate emission was found to be the highest during 10:00-10:10 am. Totally 15 μL pure exudate was collected from the stem cut between cotyledonary and unifoliolate nodes at V1 stage(unifoliolate just expanded) of young soybean seedling. Improved TRIzol method was used to extract RNA and protein from stem exudate. A phloem specific gene of Glycine max sieve element occlusion s, SEO, in exudate samples was successfully amplified by RT-PCR, which comfirmed the success of RNA extraction. SDS-PAGE showed the majority of proteins in exudate were of low molecular weight. Method proposed in this study would facilitate collection of quality exudate and enhance further investigation of mobile substances in soybean.