In order to clarify the effects of different concentrations of manganese(Mn) soaking on photosynthesis, root system, root vigor and biomass of wheat seedling, this paper performed pot experiment at the four manganese gradients of 0 g/L ,0.03 g/L,0.06 g/L and 0.12 g/L,using wheat variety ‘Xinong 979’ as the material. The results showed that:(1)Within the range 0-0.06 g/L of Mn soaking, the photosynthetic pigment, net photosynthetic rate(P_n), stomatal conductance(G_s) and water use efficiency(WUE_L) of leaf were enhanced and intercellular CO₂ concentration(C_i) was declined with increasing Mn amount. Among them, the promotion effect of 0.06 g/L of Mn soaking was mostly obvious; when Mn application level was higher than 0.06 g/L, the trend declined in P_n, transpiration rate(T_r), G_s, C_i; (2) Total root length, surface area, root volume, root vigor were the greatest in wheat seedlings under 0.06 g/L treatment, which was showed significant differences to control; (3) The trend of upground dry weight, root and rootshoot ratios in wheat seedlings appeared as single peak curves, which was the greatest under 0.06 g/L treatment. Moreover it showed significant differences to control. In general, appropriate concentration Mn soaking could improve the function of wheat leaf photosynthetic capacity and development of root under seedling stage. However, soaking wheat seeds by higher concentration Mn, would decrease growth of wheat seedling. Therefore in a comprehensive consideration of photosynthetic characteristics,root system and biomass, we propose that the optimal manganese soaking concentration is 0.06 g/L in the local with lack of manganese.