Abstract Due to inadequate rest and alcohol intake, construction workers often have pre-service fatigue before work. Many studies suggest such pre-service fatigue can result in poor working performance and high casualty risks among construction workers. To ensure workers are well-rested before duties, contractors initiate various pre-service fatigue screening approaches. Traditional screening highly relies on the site managers' subjective judgment and workers' physical appearances due to the lack of practical, objective, and automated fatigue assessment tools. In addition, compared with physical fatigue, mental fatigue is even more difficult to be recognized merely through observation. This research proposes a novel screening method capable of measuring workers' mental fatigue with wearable electroencephalography (EEG) equipment. Through analyzing the EEG spectral parameters, such as gravity frequency and power spectral entropy, this study implemented four assessing indicators and developed a quantitative method to assess a subject's mental fatigue level. To verify the proposed method, an in-lab fatigue test was conducted. The experiment results reported that the screening targets can be successfully identified by comparing their test performance and reaction time.