Objective: To study the relationship between the amount of consumed alcohol, blood alcohol concentration (BAC), and driving ability among a part of the population in Southwest China and to provide reference for the formulation of the legal limits for safe driving. Methods: Seventy-six randomly selected volunteer drivers each had three times of alcohol intake (100 ml each time). After each drank, BAC was measured with gas chromatograph and driving ability was evaluated. The drivers were grouped according to age, weight, alcohol tolerance and driving experience respectively and changes in BAC and driving ability were analyzed. Results: Average BAC and the percentage of drivers showing impaired driving ability in the groups increased after each intake of 100 ml alcohol. BAC in Group≤60 kg was more susceptible to alcohol than that in Group>60 kg. When each drank, alcohol had greater influence on drivers who had comparatively shorter driving experience. Conclusion: Volume of consumed alcohol, BAC and driving ability have direct associations among one another and are all under the influence of various factors including individual conditions. To set an appropriate legal BAC limit for safe driving should take an overall consideration of all factors.