Objective To investigate the possible pathogenesis of the cognitive function in unilateral frontal bottom laceration by follow-up study in patients after one month of the onset. Methods MMSE, Loewenstein Occupational Therapy Cognitive Assessment (LOTCA), Montreal Cognitive Assessment (MoCA), Wisconsin Card Sorting Test (WCST) scales were used to evaluate neurocognitie function in 42 patients after one month of onset of unilateral frontal bottom laceration and 45 normal controls. The wave amplitude and the latency of the endogenous composition N2, P3 of P300 were measured at the cognitive potential instrument. Level of AChE was determined by ELISA and active AChE was analyzed by the ration analyses. Stepwise multivariate regression analyzed the correlation of the overall cognitive function and the lever and active of AChE. Results The cognitive test scores in patients were significantly worse than those in normal controls. The ability of recite sentences, fluency of words, reading, understanding language,cognitive transfering decreases in the left frontal bottom laceration patients (Group A, 23 cases), while the ability of attention, action, organization, graphics depicting, abstract epitoming, logical thinking were all seriously impaired in the patients with right frontal bottom laceration (Group B, 19 cases). The latency of the endogenous composition N2, P3 in patients ( Group A: (322. 4 ± 17.0), (410. 1 ± 19.9) ms; Group B:( 308.4 ± 15.6), (385.5 ± 17.4) ms) is more lengthen ( F = 4. 084, P = 0. 018; F = 3.467, P = 0. 038 )than the normal controls ( (268.6 ± 14. 7 ), ( 369. 2 ± 15. 4 ) ms) and the wave amplitude is lower ( F =2. 986 ,P =0. 047 ;F =3. 313 ,P =0. 041 ). The latency of N2 ,P3 in Group A of is more lengthen than Group B, while the wave amplitude is higher. The difference of the active of AChE in patients and control groups had no statistical significance, however, the level of AChE in two groups had statistical significance. The comparison of the active and the total AChE in patients has also not statistical significance. The correlation of the overall cognitive function has the linear regression with the parts of the brain and the level of AChE ( rY1.2 = 0. 584, P = 0. 039; rY2.1 = 0. 726, P = 0. 017 ). The standardized regression coefficients showed the level of AChE has the biggest influence to the overall cognitive function ( |Beta| =0. 3601, rY2.1 =0. 726).Conclusions AChE may be one of the important factors in the cognitive function after frontal bottom laceration. The specific damages of cognitive function in unilateral frontal bottom laceration patients closely relate with the lesion locations in the injured frontal bottom laceration.