Humans often exhibit psychological biases in decision-making, and one of the most common phenomena is overconfidence. In the project construction process, owing to the advantages of advanced construction technology, rich historical data, and sufficient resource reserves, contractors usually overestimate their ability to control risk factors during the project planning stage and show a tendency toward overconfidence. Suppose the contractor fails to fully consider risks during the planning stage. In that case, their overconfidence tendency will result in significant negative consequences, such as their implementation being affected by uncertainties, project delays, and cost overruns. Therefore, it is necessary to analyze the specific impact of contractor overconfidence on project scheduling and propose corresponding preventive measures.This study examines the project-scheduling problem by considering contractor overconfidence in an uncertain environment. In practice, projects often face various uncertainties that may arise from the following sources: policy changes, severe weather, and equipment damage. The uncertainty theory proposed by Professor Liu Baoding provides a framework for handling such uncertainty factors and has been applied to project scheduling research. However, existing studies do not consider the psychological factors of contractor overconfidence when underestimating risk. This study introduced the overconfidence level coefficient to study the impact of contractor overconfidence on project scheduling. It then established a chance-constraint programming model based on the uncertainty theory. The goal of this model is to minimize the total project cost, considering contractor overconfidence, which considers the noise caused by risk factors into consideration. In this model, we quantitatively analyzed the influence of contractors’ underestimation of noise variance owing to overconfidence.In project management, scholarly research on overconfidence is mostly based on the principal-agent model, and no research on the impact of overconfidence on project scheduling schemes has been conducted so far. This study examines the phenomenon of overconfidence from the perspective of project planning and discusses the influence of contractors’ overconfidence psychology and behavior deviation on the arrangement of project activities, as well as the negative effects caused by such influence. It is common for the owner to set a reward and punishment mechanism based on the project duration to explore whether the risk of project delays and cost overruns caused by contractor overconfidence can be reduced by a reasonable incentive mechanism. The model is built under the circumstance that the owner sets a reward and punishment mechanism and compares and analyzes the incentive effect of the reward and punishment mechanism on the overconfident contractor. A simulation experiment was conducted to analyze whether setting reward and punishment mechanisms can effectively reduce the negative effects of the contractor's overconfidence.In this study, a genetic algorithm was designed according to the characteristics of the problem, the practicability of the algorithm was verified by a practical project, and a sensitivity analysis of the parameters was carried out. The results show that 1) overconfidence affects the contractor's project activity arrangement, resulting in a longer project completion duration and a lower probability of on-time completion, as well as accuracy of cost prediction. The contractor is more affected by a higher level of overconfidence. 2) The owner's reward and punishment mechanism based on completion duration can encourage highly confident contractors to shorten the completion duration and improve on-time completion. The mechanism was found to be more effective for highly confident contractors, whereas rational contractors were less affected. 3) The reward and punishment mechanism will give the overconfidence level a certain threshold, beyond which the influence of overconfidence will no longer intensify with the increase of the overconfidence level.This study reveals the negative impact of contractor overconfidence on project construction, verifies the effectiveness of reward and punishment mechanisms in reducing the impact of overconfidence, and has important practical significance and theoretical value for improving project management efficiency and reducing management risk.