The invention discloses a special synergist used for tank-mix pesticides and capable of promoting systemic absorption and conduction. The special synergist is composed of is water, sodium citrate andamino acid in a ratio of (15-99.49): (0.5-65): (0.01-20). The liquid medium of the special synergist is water. A preparation method for the special synergist comprises the following steps: at normal temperature, adding water into a stirring tank according to the above ratio, then adding sodium citrate, performing stirring for 10 minutes, then adding amino acid, and continuing stirring for 20 minutes to obtain the finished special synergist. The special synergist used for tank-mix pesticides is capable of promoting systemic absorption and conduction, and has high safety when applied to crops. Through the use of the special synergist, pesticide efficacy can be improved; the usage amount of pesticides can be reduced; crops, pests and weeds are promoted in rapid absorption and conduction of pesticide liquid; pesticide efficacy is given to full play; the effect of quickly eliminating diseases, insects and weeds is achieved; damage to the fruits and leaves of crops is greatly reduced; and the pollution of pesticides to food and the environment is lowered. The preparation method is simple in process, stable and safe in operation and suitable for mass production; and waste water, waste gasand waste residues are not produced in the process of production, so the method is safe and environmentally-friendly.