Abstract: Based on enzyme inhibition, a method of spectrophotometric determination of residual amounts of 6 aminoformate pesticides was proposed. By orthogonal test, the optimum conditions to obtain favourable acetylcholinesterase activity were shown as follow: ① ratio of concentration of enzyme to substrate: 6∶1; ② amount of chromogenic agent: 0.4 mg; ③ pH value of buffer solution: 8.5; ④ temperature of reaction: 40 ℃. Linear relationships between values of inhibition rate I and mass concentration of the 6 aminoformate pesticides were kept in the definite ranges. Samples of fruits and vegetables were analyzed by the proposed method and test for recovery was made by standard addition method, giving values of recovery in the range from 82.0% to 109%, with RSD′s (n=6) in the range from 2.4% to 3.6%.