The invention discloses a recycling process of sodium tetrachloroaluminate in phosphinothricin production. The process comprises the following steps that 1, mismatching and precipitation are carried out; 2, solids are filtered; 3, cooling precipitation is carried out; 4, reutilization is carried out; 5, cyclic utilization is carried out; 6, aluminum polychlorid is prepared. Sodium tetrachloroaluminate solid waste is changed into treasure, alchlor obtained after mismatching is recycled, the problem of treatment of sodium tetrachloroaluminate solid waste is solved, pollution to environment is reduced, no three waste is discharged, the atom economy of a reaction is improved, and large-scale production of phosphinothricin is facilitated. A mismatching agent and a poor solvent adopted in the process are low in price and easy to obtain, the whole process is easy and convenient to operate, and especially suitable for industrial production. Further prepared polymerization alchlor can be adopted as a water purifying agent, and is wide in application range and especially suitable for sewage treatment of chemical plants.