The co-metabolic carbon sources,dynamics and influence factors of atrazine biotransformation by genetically engineered microor- ganism(GEM)were investigated in the paper.The results showed that glucose was superior to acetate as co-metabolic carbon sources.The concentration of carbon sources affected little on atrazine transformation but much on GEM growth.The specific transformation rate(STR)of atrazine was influenced not by cell density of GEM but by atrazine concentration.Monod model was used to simulate atrazine transformation dynamics and the parameters were V_max=0.168/h and Ks=30.49mg/L. When temperature reduced,STR decreased markedly. The trans-formation was efficient in weak alkaline condition and was inhibited in acidic condition. To some extent,salinity did not affect transformation activity of GEM. Co²⁺,Fe²⁺,Fe³⁺,and Zn²⁺improved atrazine transformation,but Mn²⁺,Ni²⁺and Cu²⁺inhibited atrazine transforma-tion. The results also showed that there existed a direct correlation between adsorption and transformation of atrazine by GEM.