This paper presents a work on "improvement of the task execution deadlines on the plant construction project". It was written in a context where the mismatching for structural steel in developing countries is growing. The overall objective of this work is to see how to plan a construction project that has lagged in the execution of tasks, and then reduce this accused delay. To achieve this goal, the adopted methodology begins with an analysis of the study site construction methods, after that the data collection comes, including tasks still to be carried out, followed by a choice of methods to be used and, finally, project planning. The planning methods used are work breakdown structure and the Gantt chart, to which time deadline reduction methods such as overtime planning, night work and resource addition were applied. The completion deadlines of this project were reduced by two months. By comparing the investment cost to achieve this reduction and the financial losses caused by the delay, it is easy to see the importance of the proposed solution. This work will allow companies to avoid losing the profit they would have made if they were producing and this profit often turns out to be enormous.