Abstract: In a field experiment, the effects of biomasses on rhizobium and arbuscular mycorrhizas fungi (AMF), soybean dual symbiosis, soybean yield and soil microbes were studied. The four kinds investigated biomasses were straw, potato skins, edible fungi waste, and soybean extract liquid. Samples were determined during plant growth stages of the fourth compound leaf expanding (V5), initial pod bearing (R3) and full grain filling (R6). The results showed that all four biomasses types promoted soybean dual symbiotic system. The effects on soybean arbuscular mycorrhizas fungi were higher and longer than on rhizobium formation. Straw had the best performance not only for soybean dual symbiosis system, soil bacteria number and soil fungi number, but also for soybean yield. During R6 period, nodule number, AMF colonization and soil bacteria number increased by 238.46%, 26.28% and 131.99%, respectively, compared with the control. Soybean yield also increased by 69.78%. In practice, straw was easier to obtain and more convenient to apply than other materials. Thus straw was the most ideal biomass among the four kinds of biomass. The processing method of soybean liquid extract significant influenced soybean dual symbiosis. Nodule number was increased by 89.74% during R6 period while AMF colonization rate increased by 31.23% under soybean liquid extract treatment than under the control. The mode of soaking seeds before sowing caused more damage to soybean cotyledons. Also seedling rate was severely degraded, which resulted in relatively low yields. The edible fungi waste and potato skin had different effects on soybean dual symbiosis at the three growth stages. However, AMF colonization rate and soil fungi number in the two treatments were significantly higher than in the control during R6 period.