Abstract: Pot experiment was conducted to study the effect of special fertilizer combined synergist on yield of single rice and its mechanism. The results showed that rice special fertilizer combined with synergist promoted the growth of rice, and the total volume, total absorption area and active absorption area of rice root system significantly increased. Synergist could improve photosynthetic characteristics of lower leaves, enhance the content of chlorophyll and photosynthetic rate of rice; and the conductance to H2O and transpiration rate, inner condition of nutrient transportation and absorption power of rice root system were improved. Synergist could also increase tiller capability and dry weight accumulation of rice. The synergist treatment increased yield of rice by 8.6% than the treatment without synergist and reduced fertilizer rate by 10% and 20%.