Seed dispersal by food hoarding animals plays an important role in the successful seed-to-seedling transition and tree regeneration of many tree species bearing large-sized seeds. Small rodents, e.g., wood mice, chipmunks, and squirrels have been recognized as crucial seed dispersers in various ecosystems although they consume a large proportion of seeds. Studies have shown that seed traits (e.g., seed size, coat thickness, and nutrition) play important roles in seed dispersal. Moreover, the probability of seed survival and seedling establishment is largely dependent on the foraging behavior of animals in response to different seed traits, eventually determining plant community structure and dynamics. Seed size, one of the key seed traits, largely affects seed dispersal and scatter hoarding by food hoarding animals. However, studies on the impact of seed size on seed dispersal generate different results. In September 2012, we attached small radio transmitters (ATS R-1605) onto the nuts of Juglans mandshurica with contrasting seed sizes and tracked seed fate and dispersal distance of each nut with R-1000 receivers, to test the effect of seed size on seed dispersal of large and small seeds in the Dongfanghong Forest Park of Dailing District, Heilongjiang Province in the southern Xiaoxing'an Mountains. Seed dispersers were determined by using infrared digital cameras (Reconyx HyperFire Infrared Digital Game Camera HC600). In total, 45 large and 45 small nuts of J. mandshurica were presented to potential seed dispersers, and seed fates were tracked for 10 days after dispersal by small rodents. Our results showed that: 1) There was no significant preference of small rodents for seed selection and caching of large and small nuts of J. mandshurica. Small rodents removed all large nuts and 95.6% of small nuts, resulting in similar scatter hoarding rates of the two seed types (χ²=0.045, df=1, P=0.831); 2) There was no significant effect of seed size on the dispersal times of large and small seeds (F=2.710, df=1, P=0.103), with large and small seeds being dispersed 1.67±0.10 and 1.91±0.10 times by small rodents, respectively; 3) Large nuts of J. mandshurica were more likely to be transported further than small ones during the primary and secondary dispersal by small rodents. Moreover, both net dispersal distance and total dispersal distance of large nuts were higher than those of small nuts. Multiple dispersal processes and patterns of large and small seeds by small rodents were accurately recorded in our study. The radio telemetry technology seems to facilitate accurate evaluation of the effects of seed size on dispersal distances, further supporting the hypothesis that larger seeds are likely to be dispersed further than small ones.