The invention relates to a power grid technical renovation overhaul engineering cost management system and a control method thereof and solves a disadvantage of difficulty in effectively managing engineering cost in the prior art. The method comprises steps that projection division of a power grid technical renovation overhaul engineering project is determined; engineering work load list cost dataof different stages of one same historical engineering and of different engineerings at one same stage is analyzed; similarity matrix construction and similarity calculation are carried out; quantitative calculation and prediction are carried out; prediction cost is adjusted according to actual conditions till the prediction result is consistent with preset conditions of the power grid technicalrenovation overhaul engineering. The method is advantaged in that an engineering work load list valuation mode can be taken as a penetration point for cost prediction, rapid record of relevant data ofcost management of the power grid technical renovation overhaul engineering is realized, and work efficiency and accuracy of cost prediction are improved.