Aflatoxins, the fungal secondary metabolites, were produced by toxigenic fungi (such as Aspergillus flavus and Aspergillus parasiticus) via polyketide biosynthetic pathway. They are hepatotoxic and hepatocarcinogenic compound to human and animals. Aflatoxin B1 (AFB1) is hepatotoxins and it has been showed that AFB1 contaminated food might positively correlate with the number of hepatocelluar carcinoma cases 1. It was reported that the minimum concentration of AFB1 (10 µg per day) to induce cancer is 75 times as little as that of dimethylnitrosamine (750 µg per day) 2-6. International Agency for Research on Cancer (IARC) of World Health Organization (WHO) has classified AFB1 as class I carcinogen as slow and daily ingestion of low concentration of AFB1 was considered the potential cause of hepatocarcinoma 7-9. The function of urea cycle is to transform toxic ammonia into nontoxic urea. After secreted into the blood, urea was detoxic by kidney excretion, which avoid of the occurrence of hyperammonemia. The cycle was discovered by Hanks Kreds and it is the first metabolic cycle discovered 10-12. Carbamoylphosphate synthetase 1 (CPS1) is the starting enzyme and the key enzyme of urea synthetases. As a rate-limiting enzyme in urea synthesis, CPS1 catalyzes the synthesis of carbamoyl phosphate from NH3 and CO2 in the presence of ATP, after